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Diffstat (limited to 'node_modules/uglify-js/lib/compress.js')
| -rw-r--r-- | node_modules/uglify-js/lib/compress.js | 3997 |
1 files changed, 3997 insertions, 0 deletions
diff --git a/node_modules/uglify-js/lib/compress.js b/node_modules/uglify-js/lib/compress.js new file mode 100644 index 000000000..1d9258cf6 --- /dev/null +++ b/node_modules/uglify-js/lib/compress.js @@ -0,0 +1,3997 @@ +/*********************************************************************** + + A JavaScript tokenizer / parser / beautifier / compressor. + https://github.com/mishoo/UglifyJS2 + + -------------------------------- (C) --------------------------------- + + Author: Mihai Bazon + <mihai.bazon@gmail.com> + http://mihai.bazon.net/blog + + Distributed under the BSD license: + + Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com> + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions + are met: + + * Redistributions of source code must retain the above + copyright notice, this list of conditions and the following + disclaimer. + + * Redistributions in binary form must reproduce the above + copyright notice, this list of conditions and the following + disclaimer in the documentation and/or other materials + provided with the distribution. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY + EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE + LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, + OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR + TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF + THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + SUCH DAMAGE. + + ***********************************************************************/ + +"use strict"; + +function Compressor(options, false_by_default) { + if (!(this instanceof Compressor)) + return new Compressor(options, false_by_default); + TreeTransformer.call(this, this.before, this.after); + this.options = defaults(options, { + angular : false, + booleans : !false_by_default, + cascade : !false_by_default, + collapse_vars : !false_by_default, + comparisons : !false_by_default, + conditionals : !false_by_default, + dead_code : !false_by_default, + drop_console : false, + drop_debugger : !false_by_default, + evaluate : !false_by_default, + expression : false, + global_defs : {}, + hoist_funs : !false_by_default, + hoist_vars : false, + if_return : !false_by_default, + join_vars : !false_by_default, + keep_fargs : true, + keep_fnames : false, + keep_infinity : false, + loops : !false_by_default, + negate_iife : !false_by_default, + passes : 1, + properties : !false_by_default, + pure_getters : !false_by_default && "strict", + pure_funcs : null, + reduce_vars : !false_by_default, + screw_ie8 : true, + sequences : !false_by_default, + side_effects : !false_by_default, + switches : !false_by_default, + top_retain : null, + toplevel : !!(options && options["top_retain"]), + unsafe : false, + unsafe_comps : false, + unsafe_math : false, + unsafe_proto : false, + unused : !false_by_default, + warnings : true, + }, true); + var pure_funcs = this.options["pure_funcs"]; + if (typeof pure_funcs == "function") { + this.pure_funcs = pure_funcs; + } else { + this.pure_funcs = pure_funcs ? function(node) { + return pure_funcs.indexOf(node.expression.print_to_string()) < 0; + } : return_true; + } + var top_retain = this.options["top_retain"]; + if (top_retain instanceof RegExp) { + this.top_retain = function(def) { + return top_retain.test(def.name); + }; + } else if (typeof top_retain == "function") { + this.top_retain = top_retain; + } else if (top_retain) { + if (typeof top_retain == "string") { + top_retain = top_retain.split(/,/); + } + this.top_retain = function(def) { + return top_retain.indexOf(def.name) >= 0; + }; + } + var sequences = this.options["sequences"]; + this.sequences_limit = sequences == 1 ? 200 : sequences | 0; + this.warnings_produced = {}; +}; + +Compressor.prototype = new TreeTransformer; +merge(Compressor.prototype, { + option: function(key) { return this.options[key] }, + compress: function(node) { + if (this.option("expression")) { + node = node.process_expression(true); + } + var passes = +this.options.passes || 1; + for (var pass = 0; pass < passes && pass < 3; ++pass) { + if (pass > 0 || this.option("reduce_vars")) + node.reset_opt_flags(this, true); + node = node.transform(this); + } + if (this.option("expression")) { + node = node.process_expression(false); + } + return node; + }, + info: function() { + if (this.options.warnings == "verbose") { + AST_Node.warn.apply(AST_Node, arguments); + } + }, + warn: function(text, props) { + if (this.options.warnings) { + // only emit unique warnings + var message = string_template(text, props); + if (!(message in this.warnings_produced)) { + this.warnings_produced[message] = true; + AST_Node.warn.apply(AST_Node, arguments); + } + } + }, + clear_warnings: function() { + this.warnings_produced = {}; + }, + before: function(node, descend, in_list) { + if (node._squeezed) return node; + var was_scope = false; + if (node instanceof AST_Scope) { + node = node.hoist_declarations(this); + was_scope = true; + } + // Before https://github.com/mishoo/UglifyJS2/pull/1602 AST_Node.optimize() + // would call AST_Node.transform() if a different instance of AST_Node is + // produced after OPT(). + // This corrupts TreeWalker.stack, which cause AST look-ups to malfunction. + // Migrate and defer all children's AST_Node.transform() to below, which + // will now happen after this parent AST_Node has been properly substituted + // thus gives a consistent AST snapshot. + descend(node, this); + // Existing code relies on how AST_Node.optimize() worked, and omitting the + // following replacement call would result in degraded efficiency of both + // output and performance. + descend(node, this); + var opt = node.optimize(this); + if (was_scope && opt instanceof AST_Scope) { + opt.drop_unused(this); + descend(opt, this); + } + if (opt === node) opt._squeezed = true; + return opt; + } +}); + +(function(){ + + function OPT(node, optimizer) { + node.DEFMETHOD("optimize", function(compressor){ + var self = this; + if (self._optimized) return self; + if (compressor.has_directive("use asm")) return self; + var opt = optimizer(self, compressor); + opt._optimized = true; + return opt; + }); + }; + + OPT(AST_Node, function(self, compressor){ + return self; + }); + + AST_Node.DEFMETHOD("equivalent_to", function(node){ + return this.TYPE == node.TYPE && this.print_to_string() == node.print_to_string(); + }); + + AST_Node.DEFMETHOD("process_expression", function(insert, compressor) { + var self = this; + var tt = new TreeTransformer(function(node) { + if (insert && node instanceof AST_SimpleStatement) { + return make_node(AST_Return, node, { + value: node.body + }); + } + if (!insert && node instanceof AST_Return) { + if (compressor) { + var value = node.value && node.value.drop_side_effect_free(compressor, true); + return value ? make_node(AST_SimpleStatement, node, { + body: value + }) : make_node(AST_EmptyStatement, node); + } + return make_node(AST_SimpleStatement, node, { + body: node.value || make_node(AST_UnaryPrefix, node, { + operator: "void", + expression: make_node(AST_Number, node, { + value: 0 + }) + }) + }); + } + if (node instanceof AST_Lambda && node !== self) { + return node; + } + if (node instanceof AST_Block) { + var index = node.body.length - 1; + if (index >= 0) { + node.body[index] = node.body[index].transform(tt); + } + } + if (node instanceof AST_If) { + node.body = node.body.transform(tt); + if (node.alternative) { + node.alternative = node.alternative.transform(tt); + } + } + if (node instanceof AST_With) { + node.body = node.body.transform(tt); + } + return node; + }); + return self.transform(tt); + }); + + AST_Node.DEFMETHOD("reset_opt_flags", function(compressor, rescan){ + var reduce_vars = rescan && compressor.option("reduce_vars"); + var toplevel = compressor.option("toplevel"); + var safe_ids = Object.create(null); + var suppressor = new TreeWalker(function(node) { + if (node instanceof AST_Symbol) { + var d = node.definition(); + if (node instanceof AST_SymbolRef) d.references.push(node); + d.fixed = false; + } + }); + var tw = new TreeWalker(function(node, descend){ + node._squeezed = false; + node._optimized = false; + if (reduce_vars) { + if (node instanceof AST_Toplevel) node.globals.each(reset_def); + if (node instanceof AST_Scope) node.variables.each(reset_def); + if (node instanceof AST_SymbolRef) { + var d = node.definition(); + d.references.push(node); + if (d.fixed === undefined || !is_safe(d) + || is_modified(node, 0, node.fixed_value() instanceof AST_Lambda)) { + d.fixed = false; + } + } + if (node instanceof AST_SymbolCatch) { + node.definition().fixed = false; + } + if (node instanceof AST_VarDef) { + var d = node.name.definition(); + if (d.fixed == null) { + if (node.value) { + d.fixed = function() { + return node.value; + }; + mark(d, false); + descend(); + } else { + d.fixed = null; + } + mark(d, true); + return true; + } else if (node.value) { + d.fixed = false; + } + } + if (node instanceof AST_Defun) { + var d = node.name.definition(); + if (!toplevel && d.global || is_safe(d)) { + d.fixed = false; + } else { + d.fixed = node; + mark(d, true); + } + var save_ids = safe_ids; + safe_ids = Object.create(null); + descend(); + safe_ids = save_ids; + return true; + } + var iife; + if (node instanceof AST_Function + && !node.name + && (iife = tw.parent()) instanceof AST_Call + && iife.expression === node) { + // Virtually turn IIFE parameters into variable definitions: + // (function(a,b) {...})(c,d) => (function() {var a=c,b=d; ...})() + // So existing transformation rules can work on them. + node.argnames.forEach(function(arg, i) { + var d = arg.definition(); + d.fixed = function() { + return iife.args[i] || make_node(AST_Undefined, iife); + }; + mark(d, true); + }); + } + if (node instanceof AST_If || node instanceof AST_DWLoop) { + node.condition.walk(tw); + push(); + node.body.walk(tw); + pop(); + if (node.alternative) { + push(); + node.alternative.walk(tw); + pop(); + } + return true; + } + if (node instanceof AST_LabeledStatement) { + push(); + node.body.walk(tw); + pop(); + return true; + } + if (node instanceof AST_For) { + if (node.init) node.init.walk(tw); + push(); + if (node.condition) node.condition.walk(tw); + node.body.walk(tw); + if (node.step) node.step.walk(tw); + pop(); + return true; + } + if (node instanceof AST_ForIn) { + node.init.walk(suppressor); + node.object.walk(tw); + push(); + node.body.walk(tw); + pop(); + return true; + } + if (node instanceof AST_Catch || node instanceof AST_SwitchBranch) { + push(); + descend(); + pop(); + return true; + } + } + }); + this.walk(tw); + + function mark(def, safe) { + safe_ids[def.id] = safe; + } + + function is_safe(def) { + if (safe_ids[def.id]) { + if (def.fixed == null) { + var orig = def.orig[0]; + if (orig instanceof AST_SymbolFunarg || orig.name == "arguments") return false; + def.fixed = make_node(AST_Undefined, orig); + } + return true; + } + } + + function push() { + safe_ids = Object.create(safe_ids); + } + + function pop() { + safe_ids = Object.getPrototypeOf(safe_ids); + } + + function reset_def(def) { + if (toplevel || !def.global || def.orig[0] instanceof AST_SymbolConst) { + def.fixed = undefined; + } else { + def.fixed = false; + } + def.references = []; + def.should_replace = undefined; + } + + function is_modified(node, level, func) { + var parent = tw.parent(level); + if (is_lhs(node, parent) + || !func && parent instanceof AST_Call && parent.expression === node) { + return true; + } else if (parent instanceof AST_PropAccess && parent.expression === node) { + return !func && is_modified(parent, level + 1); + } + } + }); + + AST_SymbolRef.DEFMETHOD("fixed_value", function() { + var fixed = this.definition().fixed; + if (!fixed || fixed instanceof AST_Node) return fixed; + return fixed(); + }); + + function find_variable(compressor, name) { + var scope, i = 0; + while (scope = compressor.parent(i++)) { + if (scope instanceof AST_Scope) break; + if (scope instanceof AST_Catch) { + scope = scope.argname.definition().scope; + break; + } + } + return scope.find_variable(name); + } + + function make_node(ctor, orig, props) { + if (!props) props = {}; + if (orig) { + if (!props.start) props.start = orig.start; + if (!props.end) props.end = orig.end; + } + return new ctor(props); + }; + + function make_node_from_constant(val, orig) { + switch (typeof val) { + case "string": + return make_node(AST_String, orig, { + value: val + }); + case "number": + if (isNaN(val)) return make_node(AST_NaN, orig); + if (isFinite(val)) { + return 1 / val < 0 ? make_node(AST_UnaryPrefix, orig, { + operator: "-", + expression: make_node(AST_Number, orig, { value: -val }) + }) : make_node(AST_Number, orig, { value: val }); + } + return val < 0 ? make_node(AST_UnaryPrefix, orig, { + operator: "-", + expression: make_node(AST_Infinity, orig) + }) : make_node(AST_Infinity, orig); + case "boolean": + return make_node(val ? AST_True : AST_False, orig); + case "undefined": + return make_node(AST_Undefined, orig); + default: + if (val === null) { + return make_node(AST_Null, orig, { value: null }); + } + if (val instanceof RegExp) { + return make_node(AST_RegExp, orig, { value: val }); + } + throw new Error(string_template("Can't handle constant of type: {type}", { + type: typeof val + })); + } + }; + + // we shouldn't compress (1,func)(something) to + // func(something) because that changes the meaning of + // the func (becomes lexical instead of global). + function maintain_this_binding(parent, orig, val) { + if (parent instanceof AST_UnaryPrefix && parent.operator == "delete" + || parent instanceof AST_Call && parent.expression === orig + && (val instanceof AST_PropAccess || val instanceof AST_SymbolRef && val.name == "eval")) { + return make_node(AST_Seq, orig, { + car: make_node(AST_Number, orig, { + value: 0 + }), + cdr: val + }); + } + return val; + } + + function as_statement_array(thing) { + if (thing === null) return []; + if (thing instanceof AST_BlockStatement) return thing.body; + if (thing instanceof AST_EmptyStatement) return []; + if (thing instanceof AST_Statement) return [ thing ]; + throw new Error("Can't convert thing to statement array"); + }; + + function is_empty(thing) { + if (thing === null) return true; + if (thing instanceof AST_EmptyStatement) return true; + if (thing instanceof AST_BlockStatement) return thing.body.length == 0; + return false; + }; + + function loop_body(x) { + if (x instanceof AST_Switch) return x; + if (x instanceof AST_For || x instanceof AST_ForIn || x instanceof AST_DWLoop) { + return (x.body instanceof AST_BlockStatement ? x.body : x); + } + return x; + }; + + function is_iife_call(node) { + if (node instanceof AST_Call && !(node instanceof AST_New)) { + return node.expression instanceof AST_Function || is_iife_call(node.expression); + } + return false; + } + + function tighten_body(statements, compressor) { + var CHANGED, max_iter = 10; + do { + CHANGED = false; + if (compressor.option("angular")) { + statements = process_for_angular(statements); + } + statements = eliminate_spurious_blocks(statements); + if (compressor.option("dead_code")) { + statements = eliminate_dead_code(statements, compressor); + } + if (compressor.option("if_return")) { + statements = handle_if_return(statements, compressor); + } + if (compressor.sequences_limit > 0) { + statements = sequencesize(statements, compressor); + } + if (compressor.option("join_vars")) { + statements = join_consecutive_vars(statements, compressor); + } + if (compressor.option("collapse_vars")) { + statements = collapse_single_use_vars(statements, compressor); + } + } while (CHANGED && max_iter-- > 0); + + return statements; + + function collapse_single_use_vars(statements, compressor) { + // Iterate statements backwards looking for a statement with a var/const + // declaration immediately preceding it. Grab the rightmost var definition + // and if it has exactly one reference then attempt to replace its reference + // in the statement with the var value and then erase the var definition. + + var self = compressor.self(); + var var_defs_removed = false; + var toplevel = compressor.option("toplevel"); + for (var stat_index = statements.length; --stat_index >= 0;) { + var stat = statements[stat_index]; + if (stat instanceof AST_Definitions) continue; + + // Process child blocks of statement if present. + [stat, stat.body, stat.alternative, stat.bcatch, stat.bfinally].forEach(function(node) { + node && node.body && collapse_single_use_vars(node.body, compressor); + }); + + // The variable definition must precede a statement. + if (stat_index <= 0) break; + var prev_stat_index = stat_index - 1; + var prev_stat = statements[prev_stat_index]; + if (!(prev_stat instanceof AST_Definitions)) continue; + var var_defs = prev_stat.definitions; + if (var_defs == null) continue; + + var var_names_seen = {}; + var side_effects_encountered = false; + var lvalues_encountered = false; + var lvalues = {}; + + // Scan variable definitions from right to left. + for (var var_defs_index = var_defs.length; --var_defs_index >= 0;) { + + // Obtain var declaration and var name with basic sanity check. + var var_decl = var_defs[var_defs_index]; + if (var_decl.value == null) break; + var var_name = var_decl.name.name; + if (!var_name || !var_name.length) break; + + // Bail if we've seen a var definition of same name before. + if (var_name in var_names_seen) break; + var_names_seen[var_name] = true; + + // Only interested in cases with just one reference to the variable. + var def = self.find_variable && self.find_variable(var_name); + if (!def || !def.references || def.references.length !== 1 + || var_name == "arguments" || (!toplevel && def.global)) { + side_effects_encountered = true; + continue; + } + var ref = def.references[0]; + + // Don't replace ref if eval() or with statement in scope. + if (ref.scope.uses_eval || ref.scope.uses_with) break; + + // Constant single use vars can be replaced in any scope. + if (var_decl.value.is_constant()) { + var ctt = new TreeTransformer(function(node) { + var parent = ctt.parent(); + if (parent instanceof AST_IterationStatement + && (parent.condition === node || parent.init === node)) { + return node; + } + if (node === ref) + return replace_var(node, parent, true); + }); + stat.transform(ctt); + continue; + } + + // Restrict var replacement to constants if side effects encountered. + if (side_effects_encountered |= lvalues_encountered) continue; + + var value_has_side_effects = var_decl.value.has_side_effects(compressor); + // Non-constant single use vars can only be replaced in same scope. + if (ref.scope !== self) { + side_effects_encountered |= value_has_side_effects; + continue; + } + + // Detect lvalues in var value. + var tw = new TreeWalker(function(node){ + if (node instanceof AST_SymbolRef && is_lvalue(node, tw.parent())) { + lvalues[node.name] = lvalues_encountered = true; + } + }); + var_decl.value.walk(tw); + + // Replace the non-constant single use var in statement if side effect free. + var unwind = false; + var tt = new TreeTransformer( + function preorder(node) { + if (unwind) return node; + var parent = tt.parent(); + if (node instanceof AST_Lambda + || node instanceof AST_Try + || node instanceof AST_With + || node instanceof AST_Case + || node instanceof AST_IterationStatement + || (parent instanceof AST_If && node !== parent.condition) + || (parent instanceof AST_Conditional && node !== parent.condition) + || (node instanceof AST_SymbolRef + && value_has_side_effects + && !are_references_in_scope(node.definition(), self)) + || (parent instanceof AST_Binary + && (parent.operator == "&&" || parent.operator == "||") + && node === parent.right) + || (parent instanceof AST_Switch && node !== parent.expression)) { + return side_effects_encountered = unwind = true, node; + } + function are_references_in_scope(def, scope) { + if (def.orig.length === 1 + && def.orig[0] instanceof AST_SymbolDefun) return true; + if (def.scope !== scope) return false; + var refs = def.references; + for (var i = 0, len = refs.length; i < len; i++) { + if (refs[i].scope !== scope) return false; + } + return true; + } + }, + function postorder(node) { + if (unwind) return node; + if (node === ref) + return unwind = true, replace_var(node, tt.parent(), false); + if (side_effects_encountered |= node.has_side_effects(compressor)) + return unwind = true, node; + if (lvalues_encountered && node instanceof AST_SymbolRef && node.name in lvalues) { + side_effects_encountered = true; + return unwind = true, node; + } + } + ); + stat.transform(tt); + } + } + + // Remove extraneous empty statments in block after removing var definitions. + // Leave at least one statement in `statements`. + if (var_defs_removed) for (var i = statements.length; --i >= 0;) { + if (statements.length > 1 && statements[i] instanceof AST_EmptyStatement) + statements.splice(i, 1); + } + + return statements; + + function is_lvalue(node, parent) { + return node instanceof AST_SymbolRef && is_lhs(node, parent); + } + function replace_var(node, parent, is_constant) { + if (is_lvalue(node, parent)) return node; + + // Remove var definition and return its value to the TreeTransformer to replace. + var value = maintain_this_binding(parent, node, var_decl.value); + var_decl.value = null; + + var_defs.splice(var_defs_index, 1); + if (var_defs.length === 0) { + statements[prev_stat_index] = make_node(AST_EmptyStatement, self); + var_defs_removed = true; + } + // Further optimize statement after substitution. + stat.reset_opt_flags(compressor); + + compressor.info("Collapsing " + (is_constant ? "constant" : "variable") + + " " + var_name + " [{file}:{line},{col}]", node.start); + CHANGED = true; + return value; + } + } + + function process_for_angular(statements) { + function has_inject(comment) { + return /@ngInject/.test(comment.value); + } + function make_arguments_names_list(func) { + return func.argnames.map(function(sym){ + return make_node(AST_String, sym, { value: sym.name }); + }); + } + function make_array(orig, elements) { + return make_node(AST_Array, orig, { elements: elements }); + } + function make_injector(func, name) { + return make_node(AST_SimpleStatement, func, { + body: make_node(AST_Assign, func, { + operator: "=", + left: make_node(AST_Dot, name, { + expression: make_node(AST_SymbolRef, name, name), + property: "$inject" + }), + right: make_array(func, make_arguments_names_list(func)) + }) + }); + } + function check_expression(body) { + if (body && body.args) { + // if this is a function call check all of arguments passed + body.args.forEach(function(argument, index, array) { + var comments = argument.start.comments_before; + // if the argument is function preceded by @ngInject + if (argument instanceof AST_Lambda && comments.length && has_inject(comments[0])) { + // replace the function with an array of names of its parameters and function at the end + array[index] = make_array(argument, make_arguments_names_list(argument).concat(argument)); + } + }); + // if this is chained call check previous one recursively + if (body.expression && body.expression.expression) { + check_expression(body.expression.expression); + } + } + } + return statements.reduce(function(a, stat){ + a.push(stat); + + if (stat.body && stat.body.args) { + check_expression(stat.body); + } else { + var token = stat.start; + var comments = token.comments_before; + if (comments && comments.length > 0) { + var last = comments.pop(); + if (has_inject(last)) { + // case 1: defun + if (stat instanceof AST_Defun) { + a.push(make_injector(stat, stat.name)); + } + else if (stat instanceof AST_Definitions) { + stat.definitions.forEach(function(def) { + if (def.value && def.value instanceof AST_Lambda) { + a.push(make_injector(def.value, def.name)); + } + }); + } + else { + compressor.warn("Unknown statement marked with @ngInject [{file}:{line},{col}]", token); + } + } + } + } + + return a; + }, []); + } + + function eliminate_spurious_blocks(statements) { + var seen_dirs = []; + return statements.reduce(function(a, stat){ + if (stat instanceof AST_BlockStatement) { + CHANGED = true; + a.push.apply(a, eliminate_spurious_blocks(stat.body)); + } else if (stat instanceof AST_EmptyStatement) { + CHANGED = true; + } else if (stat instanceof AST_Directive) { + if (seen_dirs.indexOf(stat.value) < 0) { + a.push(stat); + seen_dirs.push(stat.value); + } else { + CHANGED = true; + } + } else { + a.push(stat); + } + return a; + }, []); + }; + + function handle_if_return(statements, compressor) { + var self = compressor.self(); + var multiple_if_returns = has_multiple_if_returns(statements); + var in_lambda = self instanceof AST_Lambda; + var ret = []; // Optimized statements, build from tail to front + loop: for (var i = statements.length; --i >= 0;) { + var stat = statements[i]; + switch (true) { + case (in_lambda && stat instanceof AST_Return && !stat.value && ret.length == 0): + CHANGED = true; + // note, ret.length is probably always zero + // because we drop unreachable code before this + // step. nevertheless, it's good to check. + continue loop; + case stat instanceof AST_If: + if (stat.body instanceof AST_Return) { + //--- + // pretty silly case, but: + // if (foo()) return; return; ==> foo(); return; + if (((in_lambda && ret.length == 0) + || (ret[0] instanceof AST_Return && !ret[0].value)) + && !stat.body.value && !stat.alternative) { + CHANGED = true; + var cond = make_node(AST_SimpleStatement, stat.condition, { + body: stat.condition + }); + ret.unshift(cond); + continue loop; + } + //--- + // if (foo()) return x; return y; ==> return foo() ? x : y; + if (ret[0] instanceof AST_Return && stat.body.value && ret[0].value && !stat.alternative) { + CHANGED = true; + stat = stat.clone(); + stat.alternative = ret[0]; + ret[0] = stat.transform(compressor); + continue loop; + } + //--- + // if (foo()) return x; [ return ; ] ==> return foo() ? x : undefined; + if (multiple_if_returns && (ret.length == 0 || ret[0] instanceof AST_Return) + && stat.body.value && !stat.alternative && in_lambda) { + CHANGED = true; + stat = stat.clone(); + stat.alternative = ret[0] || make_node(AST_Return, stat, { + value: null + }); + ret[0] = stat.transform(compressor); + continue loop; + } + //--- + // if (foo()) return; [ else x... ]; y... ==> if (!foo()) { x...; y... } + if (!stat.body.value && in_lambda) { + CHANGED = true; + stat = stat.clone(); + stat.condition = stat.condition.negate(compressor); + var body = as_statement_array(stat.alternative).concat(ret); + var funs = extract_functions_from_statement_array(body); + stat.body = make_node(AST_BlockStatement, stat, { + body: body + }); + stat.alternative = null; + ret = funs.concat([ stat.transform(compressor) ]); + continue loop; + } + + //--- + // if (a) return b; if (c) return d; e; ==> return a ? b : c ? d : void e; + // + // if sequences is not enabled, this can lead to an endless loop (issue #866). + // however, with sequences on this helps producing slightly better output for + // the example code. + if (compressor.option("sequences") + && i > 0 && statements[i - 1] instanceof AST_If && statements[i - 1].body instanceof AST_Return + && ret.length == 1 && in_lambda && ret[0] instanceof AST_SimpleStatement + && !stat.alternative) { + CHANGED = true; + ret.push(make_node(AST_Return, ret[0], { + value: null + }).transform(compressor)); + ret.unshift(stat); + continue loop; + } + } + + var ab = aborts(stat.body); + var lct = ab instanceof AST_LoopControl ? compressor.loopcontrol_target(ab) : null; + if (ab && ((ab instanceof AST_Return && !ab.value && in_lambda) + || (ab instanceof AST_Continue && self === loop_body(lct)) + || (ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct))) { + if (ab.label) { + remove(ab.label.thedef.references, ab); + } + CHANGED = true; + var body = as_statement_array(stat.body).slice(0, -1); + stat = stat.clone(); + stat.condition = stat.condition.negate(compressor); + stat.body = make_node(AST_BlockStatement, stat, { + body: as_statement_array(stat.alternative).concat(ret) + }); + stat.alternative = make_node(AST_BlockStatement, stat, { + body: body + }); + ret = [ stat.transform(compressor) ]; + continue loop; + } + + var ab = aborts(stat.alternative); + var lct = ab instanceof AST_LoopControl ? compressor.loopcontrol_target(ab) : null; + if (ab && ((ab instanceof AST_Return && !ab.value && in_lambda) + || (ab instanceof AST_Continue && self === loop_body(lct)) + || (ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct))) { + if (ab.label) { + remove(ab.label.thedef.references, ab); + } + CHANGED = true; + stat = stat.clone(); + stat.body = make_node(AST_BlockStatement, stat.body, { + body: as_statement_array(stat.body).concat(ret) + }); + stat.alternative = make_node(AST_BlockStatement, stat.alternative, { + body: as_statement_array(stat.alternative).slice(0, -1) + }); + ret = [ stat.transform(compressor) ]; + continue loop; + } + + ret.unshift(stat); + break; + default: + ret.unshift(stat); + break; + } + } + return ret; + + function has_multiple_if_returns(statements) { + var n = 0; + for (var i = statements.length; --i >= 0;) { + var stat = statements[i]; + if (stat instanceof AST_If && stat.body instanceof AST_Return) { + if (++n > 1) return true; + } + } + return false; + } + }; + + function eliminate_dead_code(statements, compressor) { + var has_quit = false; + var orig = statements.length; + var self = compressor.self(); + statements = statements.reduce(function(a, stat){ + if (has_quit) { + extract_declarations_from_unreachable_code(compressor, stat, a); + } else { + if (stat instanceof AST_LoopControl) { + var lct = compressor.loopcontrol_target(stat); + if ((stat instanceof AST_Break + && !(lct instanceof AST_IterationStatement) + && loop_body(lct) === self) || (stat instanceof AST_Continue + && loop_body(lct) === self)) { + if (stat.label) { + remove(stat.label.thedef.references, stat); + } + } else { + a.push(stat); + } + } else { + a.push(stat); + } + if (aborts(stat)) has_quit = true; + } + return a; + }, []); + CHANGED = statements.length != orig; + return statements; + }; + + function sequencesize(statements, compressor) { + if (statements.length < 2) return statements; + var seq = [], ret = []; + function push_seq() { + seq = AST_Seq.from_array(seq); + if (seq) ret.push(make_node(AST_SimpleStatement, seq, { + body: seq + })); + seq = []; + }; + statements.forEach(function(stat){ + if (stat instanceof AST_SimpleStatement) { + if (seqLength(seq) >= compressor.sequences_limit) push_seq(); + var body = stat.body; + if (seq.length > 0) body = body.drop_side_effect_free(compressor); + if (body) seq.push(body); + } else { + push_seq(); + ret.push(stat); + } + }); + push_seq(); + ret = sequencesize_2(ret, compressor); + CHANGED = ret.length != statements.length; + return ret; + }; + + function seqLength(a) { + for (var len = 0, i = 0; i < a.length; ++i) { + var stat = a[i]; + if (stat instanceof AST_Seq) { + len += stat.len(); + } else { + len++; + } + } + return len; + }; + + function sequencesize_2(statements, compressor) { + function cons_seq(right) { + ret.pop(); + var left = prev.body; + if (left instanceof AST_Seq) { + left.add(right); + } else { + left = AST_Seq.cons(left, right); + } + return left.transform(compressor); + }; + var ret = [], prev = null; + statements.forEach(function(stat){ + if (prev) { + if (stat instanceof AST_For) { + var opera = {}; + try { + prev.body.walk(new TreeWalker(function(node){ + if (node instanceof AST_Binary && node.operator == "in") + throw opera; + })); + if (stat.init && !(stat.init instanceof AST_Definitions)) { + stat.init = cons_seq(stat.init); + } + else if (!stat.init) { + stat.init = prev.body.drop_side_effect_free(compressor); + ret.pop(); + } + } catch(ex) { + if (ex !== opera) throw ex; + } + } + else if (stat instanceof AST_If) { + stat.condition = cons_seq(stat.condition); + } + else if (stat instanceof AST_With) { + stat.expression = cons_seq(stat.expression); + } + else if (stat instanceof AST_Exit && stat.value) { + stat.value = cons_seq(stat.value); + } + else if (stat instanceof AST_Exit) { + stat.value = cons_seq(make_node(AST_Undefined, stat).transform(compressor)); + } + else if (stat instanceof AST_Switch) { + stat.expression = cons_seq(stat.expression); + } + } + ret.push(stat); + prev = stat instanceof AST_SimpleStatement ? stat : null; + }); + return ret; + }; + + function join_consecutive_vars(statements, compressor) { + var prev = null; + return statements.reduce(function(a, stat){ + if (stat instanceof AST_Definitions && prev && prev.TYPE == stat.TYPE) { + prev.definitions = prev.definitions.concat(stat.definitions); + CHANGED = true; + } + else if (stat instanceof AST_For + && prev instanceof AST_Var + && (!stat.init || stat.init.TYPE == prev.TYPE)) { + CHANGED = true; + a.pop(); + if (stat.init) { + stat.init.definitions = prev.definitions.concat(stat.init.definitions); + } else { + stat.init = prev; + } + a.push(stat); + prev = stat; + } + else { + prev = stat; + a.push(stat); + } + return a; + }, []); + }; + + }; + + function extract_functions_from_statement_array(statements) { + var funs = []; + for (var i = statements.length - 1; i >= 0; --i) { + var stat = statements[i]; + if (stat instanceof AST_Defun) { + statements.splice(i, 1); + funs.unshift(stat); + } + } + return funs; + } + + function extract_declarations_from_unreachable_code(compressor, stat, target) { + if (!(stat instanceof AST_Defun)) { + compressor.warn("Dropping unreachable code [{file}:{line},{col}]", stat.start); + } + stat.walk(new TreeWalker(function(node){ + if (node instanceof AST_Definitions) { + compressor.warn("Declarations in unreachable code! [{file}:{line},{col}]", node.start); + node.remove_initializers(); + target.push(node); + return true; + } + if (node instanceof AST_Defun) { + target.push(node); + return true; + } + if (node instanceof AST_Scope) { + return true; + } + })); + }; + + function is_undefined(node, compressor) { + return node.is_undefined + || node instanceof AST_Undefined + || node instanceof AST_UnaryPrefix + && node.operator == "void" + && !node.expression.has_side_effects(compressor); + } + + // may_eq_null() + // returns true if this node may evaluate to null or undefined + (function(def) { + AST_Node.DEFMETHOD("may_eq_null", function(compressor) { + var pure_getters = compressor.option("pure_getters"); + return !pure_getters || this._eq_null(pure_getters); + }); + + function is_strict(pure_getters) { + return /strict/.test(pure_getters); + } + + def(AST_Node, is_strict); + def(AST_Null, return_true); + def(AST_Undefined, return_true); + def(AST_Constant, return_false); + def(AST_Array, return_false); + def(AST_Object, return_false); + def(AST_Function, return_false); + def(AST_UnaryPostfix, return_false); + def(AST_UnaryPrefix, function() { + return this.operator == "void"; + }); + def(AST_Binary, function(pure_getters) { + switch (this.operator) { + case "&&": + return this.left._eq_null(pure_getters); + case "||": + return this.left._eq_null(pure_getters) + && this.right._eq_null(pure_getters); + default: + return false; + } + }) + def(AST_Assign, function(pure_getters) { + return this.operator == "=" + && this.right._eq_null(pure_getters); + }) + def(AST_Conditional, function(pure_getters) { + return this.consequent._eq_null(pure_getters) + || this.alternative._eq_null(pure_getters); + }) + def(AST_Seq, function(pure_getters) { + return this.cdr._eq_null(pure_getters); + }); + def(AST_SymbolRef, function(pure_getters) { + if (this.is_undefined) return true; + if (!is_strict(pure_getters)) return false; + var fixed = this.fixed_value(); + return !fixed || fixed._eq_null(pure_getters); + }); + })(function(node, func) { + node.DEFMETHOD("_eq_null", func); + }); + + /* -----[ boolean/negation helpers ]----- */ + + // methods to determine whether an expression has a boolean result type + (function (def){ + var unary_bool = [ "!", "delete" ]; + var binary_bool = [ "in", "instanceof", "==", "!=", "===", "!==", "<", "<=", ">=", ">" ]; + def(AST_Node, return_false); + def(AST_UnaryPrefix, function(){ + return member(this.operator, unary_bool); + }); + def(AST_Binary, function(){ + return member(this.operator, binary_bool) || + ( (this.operator == "&&" || this.operator == "||") && + this.left.is_boolean() && this.right.is_boolean() ); + }); + def(AST_Conditional, function(){ + return this.consequent.is_boolean() && this.alternative.is_boolean(); + }); + def(AST_Assign, function(){ + return this.operator == "=" && this.right.is_boolean(); + }); + def(AST_Seq, function(){ + return this.cdr.is_boolean(); + }); + def(AST_True, return_true); + def(AST_False, return_true); + })(function(node, func){ + node.DEFMETHOD("is_boolean", func); + }); + + // methods to determine if an expression has a numeric result type + (function (def){ + def(AST_Node, return_false); + def(AST_Number, return_true); + var unary = makePredicate("+ - ~ ++ --"); + def(AST_Unary, function(){ + return unary(this.operator); + }); + var binary = makePredicate("- * / % & | ^ << >> >>>"); + def(AST_Binary, function(compressor){ + return binary(this.operator) || this.operator == "+" + && this.left.is_number(compressor) + && this.right.is_number(compressor); + }); + def(AST_Assign, function(compressor){ + return binary(this.operator.slice(0, -1)) + || this.operator == "=" && this.right.is_number(compressor); + }); + def(AST_Seq, function(compressor){ + return this.cdr.is_number(compressor); + }); + def(AST_Conditional, function(compressor){ + return this.consequent.is_number(compressor) && this.alternative.is_number(compressor); + }); + })(function(node, func){ + node.DEFMETHOD("is_number", func); + }); + + // methods to determine if an expression has a string result type + (function (def){ + def(AST_Node, return_false); + def(AST_String, return_true); + def(AST_UnaryPrefix, function(){ + return this.operator == "typeof"; + }); + def(AST_Binary, function(compressor){ + return this.operator == "+" && + (this.left.is_string(compressor) || this.right.is_string(compressor)); + }); + def(AST_Assign, function(compressor){ + return (this.operator == "=" || this.operator == "+=") && this.right.is_string(compressor); + }); + def(AST_Seq, function(compressor){ + return this.cdr.is_string(compressor); + }); + def(AST_Conditional, function(compressor){ + return this.consequent.is_string(compressor) && this.alternative.is_string(compressor); + }); + })(function(node, func){ + node.DEFMETHOD("is_string", func); + }); + + var unary_side_effects = makePredicate("delete ++ --"); + + function is_lhs(node, parent) { + if (parent instanceof AST_Unary && unary_side_effects(parent.operator)) return parent.expression; + if (parent instanceof AST_Assign && parent.left === node) return node; + } + + (function (def){ + AST_Node.DEFMETHOD("resolve_defines", function(compressor) { + if (!compressor.option("global_defs")) return; + var def = this._find_defs(compressor, ""); + if (def) { + var node, parent = this, level = 0; + do { + node = parent; + parent = compressor.parent(level++); + } while (parent instanceof AST_PropAccess && parent.expression === node); + if (is_lhs(node, parent)) { + compressor.warn('global_defs ' + this.print_to_string() + ' redefined [{file}:{line},{col}]', this.start); + } else { + return def; + } + } + }); + function to_node(value, orig) { + if (value instanceof AST_Node) return make_node(value.CTOR, orig, value); + if (Array.isArray(value)) return make_node(AST_Array, orig, { + elements: value.map(function(value) { + return to_node(value, orig); + }) + }); + if (value && typeof value == "object") { + var props = []; + for (var key in value) { + props.push(make_node(AST_ObjectKeyVal, orig, { + key: key, + value: to_node(value[key], orig) + })); + } + return make_node(AST_Object, orig, { + properties: props + }); + } + return make_node_from_constant(value, orig); + } + def(AST_Node, noop); + def(AST_Dot, function(compressor, suffix){ + return this.expression._find_defs(compressor, "." + this.property + suffix); + }); + def(AST_SymbolRef, function(compressor, suffix){ + if (!this.global()) return; + var name; + var defines = compressor.option("global_defs"); + if (defines && HOP(defines, (name = this.name + suffix))) { + var node = to_node(defines[name], this); + var top = compressor.find_parent(AST_Toplevel); + node.walk(new TreeWalker(function(node) { + if (node instanceof AST_SymbolRef) { + node.scope = top; + node.thedef = top.def_global(node); + } + })); + return node; + } + }); + })(function(node, func){ + node.DEFMETHOD("_find_defs", func); + }); + + function best_of_expression(ast1, ast2) { + return ast1.print_to_string().length > + ast2.print_to_string().length + ? ast2 : ast1; + } + + function best_of_statement(ast1, ast2) { + return best_of_expression(make_node(AST_SimpleStatement, ast1, { + body: ast1 + }), make_node(AST_SimpleStatement, ast2, { + body: ast2 + })).body; + } + + function best_of(compressor, ast1, ast2) { + return (first_in_statement(compressor) ? best_of_statement : best_of_expression)(ast1, ast2); + } + + // methods to evaluate a constant expression + (function (def){ + // If the node has been successfully reduced to a constant, + // then its value is returned; otherwise the element itself + // is returned. + // They can be distinguished as constant value is never a + // descendant of AST_Node. + AST_Node.DEFMETHOD("evaluate", function(compressor){ + if (!compressor.option("evaluate")) return this; + try { + var val = this._eval(compressor); + return !val || val instanceof RegExp || typeof val != "object" ? val : this; + } catch(ex) { + if (ex !== def) throw ex; + return this; + } + }); + var unaryPrefix = makePredicate("! ~ - + void"); + AST_Node.DEFMETHOD("is_constant", function(){ + // Accomodate when compress option evaluate=false + // as well as the common constant expressions !0 and -1 + if (this instanceof AST_Constant) { + return !(this instanceof AST_RegExp); + } else { + return this instanceof AST_UnaryPrefix + && this.expression instanceof AST_Constant + && unaryPrefix(this.operator); + } + }); + // Obtain the constant value of an expression already known to be constant. + // Result only valid iff this.is_constant() is true. + AST_Node.DEFMETHOD("constant_value", function(compressor){ + // Accomodate when option evaluate=false. + if (this instanceof AST_Constant && !(this instanceof AST_RegExp)) { + return this.value; + } + // Accomodate the common constant expressions !0 and -1 when option evaluate=false. + if (this instanceof AST_UnaryPrefix + && this.expression instanceof AST_Constant) switch (this.operator) { + case "!": + return !this.expression.value; + case "~": + return ~this.expression.value; + case "-": + return -this.expression.value; + case "+": + return +this.expression.value; + default: + throw new Error(string_template("Cannot evaluate unary expression {value}", { + value: this.print_to_string() + })); + } + var result = this.evaluate(compressor); + if (result !== this) { + return result; + } + throw new Error(string_template("Cannot evaluate constant [{file}:{line},{col}]", this.start)); + }); + def(AST_Statement, function(){ + throw new Error(string_template("Cannot evaluate a statement [{file}:{line},{col}]", this.start)); + }); + def(AST_Lambda, function(){ + throw def; + }); + function ev(node, compressor) { + if (!compressor) throw new Error("Compressor must be passed"); + + return node._eval(compressor); + }; + def(AST_Node, function(){ + throw def; // not constant + }); + def(AST_Constant, function(){ + return this.getValue(); + }); + def(AST_Array, function(compressor){ + if (compressor.option("unsafe")) { + return this.elements.map(function(element) { + return ev(element, compressor); + }); + } + throw def; + }); + def(AST_Object, function(compressor){ + if (compressor.option("unsafe")) { + var val = {}; + for (var i = 0, len = this.properties.length; i < len; i++) { + var prop = this.properties[i]; + var key = prop.key; + if (key instanceof AST_Symbol) { + key = key.name; + } else if (key instanceof AST_Node) { + key = ev(key, compressor); + } + if (typeof Object.prototype[key] === 'function') { + throw def; + } + val[key] = ev(prop.value, compressor); + } + return val; + } + throw def; + }); + def(AST_UnaryPrefix, function(compressor){ + var e = this.expression; + switch (this.operator) { + case "!": return !ev(e, compressor); + case "typeof": + // Function would be evaluated to an array and so typeof would + // incorrectly return 'object'. Hence making is a special case. + if (e instanceof AST_Function) return typeof function(){}; + + e = ev(e, compressor); + + // typeof <RegExp> returns "object" or "function" on different platforms + // so cannot evaluate reliably + if (e instanceof RegExp) throw def; + + return typeof e; + case "void": return void ev(e, compressor); + case "~": return ~ev(e, compressor); + case "-": return -ev(e, compressor); + case "+": return +ev(e, compressor); + } + throw def; + }); + def(AST_Binary, function(c){ + var left = this.left, right = this.right, result; + switch (this.operator) { + case "&&" : result = ev(left, c) && ev(right, c); break; + case "||" : result = ev(left, c) || ev(right, c); break; + case "|" : result = ev(left, c) | ev(right, c); break; + case "&" : result = ev(left, c) & ev(right, c); break; + case "^" : result = ev(left, c) ^ ev(right, c); break; + case "+" : result = ev(left, c) + ev(right, c); break; + case "*" : result = ev(left, c) * ev(right, c); break; + case "/" : result = ev(left, c) / ev(right, c); break; + case "%" : result = ev(left, c) % ev(right, c); break; + case "-" : result = ev(left, c) - ev(right, c); break; + case "<<" : result = ev(left, c) << ev(right, c); break; + case ">>" : result = ev(left, c) >> ev(right, c); break; + case ">>>" : result = ev(left, c) >>> ev(right, c); break; + case "==" : result = ev(left, c) == ev(right, c); break; + case "===" : result = ev(left, c) === ev(right, c); break; + case "!=" : result = ev(left, c) != ev(right, c); break; + case "!==" : result = ev(left, c) !== ev(right, c); break; + case "<" : result = ev(left, c) < ev(right, c); break; + case "<=" : result = ev(left, c) <= ev(right, c); break; + case ">" : result = ev(left, c) > ev(right, c); break; + case ">=" : result = ev(left, c) >= ev(right, c); break; + default: + throw def; + } + if (isNaN(result) && c.find_parent(AST_With)) { + // leave original expression as is + throw def; + } + return result; + }); + def(AST_Conditional, function(compressor){ + return ev(this.condition, compressor) + ? ev(this.consequent, compressor) + : ev(this.alternative, compressor); + }); + def(AST_SymbolRef, function(compressor){ + if (this._evaluating) throw def; + this._evaluating = true; + try { + var fixed = this.fixed_value(); + if (compressor.option("reduce_vars") && fixed) { + if (compressor.option("unsafe")) { + if (!HOP(fixed, "_evaluated")) { + fixed._evaluated = ev(fixed, compressor); + } + return fixed._evaluated; + } + return ev(fixed, compressor); + } + } finally { + this._evaluating = false; + } + throw def; + }); + def(AST_PropAccess, function(compressor){ + if (compressor.option("unsafe")) { + var key = this.property; + if (key instanceof AST_Node) { + key = ev(key, compressor); + } + var val = ev(this.expression, compressor); + if (val && HOP(val, key)) { + return val[key]; + } + } + throw def; + }); + })(function(node, func){ + node.DEFMETHOD("_eval", func); + }); + + // method to negate an expression + (function(def){ + function basic_negation(exp) { + return make_node(AST_UnaryPrefix, exp, { + operator: "!", + expression: exp + }); + } + function best(orig, alt, first_in_statement) { + var negated = basic_negation(orig); + if (first_in_statement) { + var stat = make_node(AST_SimpleStatement, alt, { + body: alt + }); + return best_of_expression(negated, stat) === stat ? alt : negated; + } + return best_of_expression(negated, alt); + } + def(AST_Node, function(){ + return basic_negation(this); + }); + def(AST_Statement, function(){ + throw new Error("Cannot negate a statement"); + }); + def(AST_Function, function(){ + return basic_negation(this); + }); + def(AST_UnaryPrefix, function(){ + if (this.operator == "!") + return this.expression; + return basic_negation(this); + }); + def(AST_Seq, function(compressor){ + var self = this.clone(); + self.cdr = self.cdr.negate(compressor); + return self; + }); + def(AST_Conditional, function(compressor, first_in_statement){ + var self = this.clone(); + self.consequent = self.consequent.negate(compressor); + self.alternative = self.alternative.negate(compressor); + return best(this, self, first_in_statement); + }); + def(AST_Binary, function(compressor, first_in_statement){ + var self = this.clone(), op = this.operator; + if (compressor.option("unsafe_comps")) { + switch (op) { + case "<=" : self.operator = ">" ; return self; + case "<" : self.operator = ">=" ; return self; + case ">=" : self.operator = "<" ; return self; + case ">" : self.operator = "<=" ; return self; + } + } + switch (op) { + case "==" : self.operator = "!="; return self; + case "!=" : self.operator = "=="; return self; + case "===": self.operator = "!=="; return self; + case "!==": self.operator = "==="; return self; + case "&&": + self.operator = "||"; + self.left = self.left.negate(compressor, first_in_statement); + self.right = self.right.negate(compressor); + return best(this, self, first_in_statement); + case "||": + self.operator = "&&"; + self.left = self.left.negate(compressor, first_in_statement); + self.right = self.right.negate(compressor); + return best(this, self, first_in_statement); + } + return basic_negation(this); + }); + })(function(node, func){ + node.DEFMETHOD("negate", function(compressor, first_in_statement){ + return func.call(this, compressor, first_in_statement); + }); + }); + + AST_Call.DEFMETHOD("has_pure_annotation", function(compressor) { + if (!compressor.option("side_effects")) return false; + if (this.pure !== undefined) return this.pure; + var pure = false; + var comments, last_comment; + if (this.start + && (comments = this.start.comments_before) + && comments.length + && /[@#]__PURE__/.test((last_comment = comments[comments.length - 1]).value)) { + pure = last_comment; + } + return this.pure = pure; + }); + + // determine if expression has side effects + (function(def){ + def(AST_Node, return_true); + + def(AST_EmptyStatement, return_false); + def(AST_Constant, return_false); + def(AST_This, return_false); + + def(AST_Call, function(compressor){ + if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) return true; + for (var i = this.args.length; --i >= 0;) { + if (this.args[i].has_side_effects(compressor)) + return true; + } + return false; + }); + + function any(list, compressor) { + for (var i = list.length; --i >= 0;) + if (list[i].has_side_effects(compressor)) + return true; + return false; + } + + def(AST_Block, function(compressor){ + return any(this.body, compressor); + }); + def(AST_Switch, function(compressor){ + return this.expression.has_side_effects(compressor) + || any(this.body, compressor); + }); + def(AST_Case, function(compressor){ + return this.expression.has_side_effects(compressor) + || any(this.body, compressor); + }); + def(AST_Try, function(compressor){ + return any(this.body, compressor) + || this.bcatch && this.bcatch.has_side_effects(compressor) + || this.bfinally && this.bfinally.has_side_effects(compressor); + }); + def(AST_If, function(compressor){ + return this.condition.has_side_effects(compressor) + || this.body && this.body.has_side_effects(compressor) + || this.alternative && this.alternative.has_side_effects(compressor); + }); + def(AST_LabeledStatement, function(compressor){ + return this.body.has_side_effects(compressor); + }); + def(AST_SimpleStatement, function(compressor){ + return this.body.has_side_effects(compressor); + }); + def(AST_Defun, return_true); + def(AST_Function, return_false); + def(AST_Binary, function(compressor){ + return this.left.has_side_effects(compressor) + || this.right.has_side_effects(compressor); + }); + def(AST_Assign, return_true); + def(AST_Conditional, function(compressor){ + return this.condition.has_side_effects(compressor) + || this.consequent.has_side_effects(compressor) + || this.alternative.has_side_effects(compressor); + }); + def(AST_Unary, function(compressor){ + return unary_side_effects(this.operator) + || this.expression.has_side_effects(compressor); + }); + def(AST_SymbolRef, function(compressor){ + return this.undeclared(); + }); + def(AST_Object, function(compressor){ + return any(this.properties, compressor); + }); + def(AST_ObjectProperty, function(compressor){ + return this.value.has_side_effects(compressor); + }); + def(AST_Array, function(compressor){ + return any(this.elements, compressor); + }); + def(AST_Dot, function(compressor){ + return this.expression.may_eq_null(compressor) + || this.expression.has_side_effects(compressor); + }); + def(AST_Sub, function(compressor){ + return this.expression.may_eq_null(compressor) + || this.expression.has_side_effects(compressor) + || this.property.has_side_effects(compressor); + }); + def(AST_Seq, function(compressor){ + return this.car.has_side_effects(compressor) + || this.cdr.has_side_effects(compressor); + }); + })(function(node, func){ + node.DEFMETHOD("has_side_effects", func); + }); + + // tell me if a statement aborts + function aborts(thing) { + return thing && thing.aborts(); + }; + (function(def){ + def(AST_Statement, return_null); + def(AST_Jump, return_this); + function block_aborts(){ + var n = this.body.length; + return n > 0 && aborts(this.body[n - 1]); + }; + def(AST_BlockStatement, block_aborts); + def(AST_SwitchBranch, block_aborts); + def(AST_If, function(){ + return this.alternative && aborts(this.body) && aborts(this.alternative) && this; + }); + })(function(node, func){ + node.DEFMETHOD("aborts", func); + }); + + /* -----[ optimizers ]----- */ + + OPT(AST_Directive, function(self, compressor){ + if (compressor.has_directive(self.value) !== self) { + return make_node(AST_EmptyStatement, self); + } + return self; + }); + + OPT(AST_Debugger, function(self, compressor){ + if (compressor.option("drop_debugger")) + return make_node(AST_EmptyStatement, self); + return self; + }); + + OPT(AST_LabeledStatement, function(self, compressor){ + if (self.body instanceof AST_Break + && compressor.loopcontrol_target(self.body) === self.body) { + return make_node(AST_EmptyStatement, self); + } + return self.label.references.length == 0 ? self.body : self; + }); + + OPT(AST_Block, function(self, compressor){ + self.body = tighten_body(self.body, compressor); + return self; + }); + + OPT(AST_BlockStatement, function(self, compressor){ + self.body = tighten_body(self.body, compressor); + switch (self.body.length) { + case 1: return self.body[0]; + case 0: return make_node(AST_EmptyStatement, self); + } + return self; + }); + + AST_Scope.DEFMETHOD("drop_unused", function(compressor){ + var self = this; + if (compressor.has_directive("use asm")) return self; + var toplevel = compressor.option("toplevel"); + if (compressor.option("unused") + && (!(self instanceof AST_Toplevel) || toplevel) + && !self.uses_eval + && !self.uses_with) { + var assign_as_unused = !/keep_assign/.test(compressor.option("unused")); + var drop_funcs = /funcs/.test(toplevel); + var drop_vars = /vars/.test(toplevel); + if (!(self instanceof AST_Toplevel) || toplevel == true) { + drop_funcs = drop_vars = true; + } + var in_use = []; + var in_use_ids = Object.create(null); // avoid expensive linear scans of in_use + if (self instanceof AST_Toplevel && compressor.top_retain) { + self.variables.each(function(def) { + if (compressor.top_retain(def) && !(def.id in in_use_ids)) { + in_use_ids[def.id] = true; + in_use.push(def); + } + }); + } + var initializations = new Dictionary(); + // pass 1: find out which symbols are directly used in + // this scope (not in nested scopes). + var scope = this; + var tw = new TreeWalker(function(node, descend){ + if (node !== self) { + if (node instanceof AST_Defun) { + if (!drop_funcs && scope === self) { + var node_def = node.name.definition(); + if (!(node_def.id in in_use_ids)) { + in_use_ids[node_def.id] = true; + in_use.push(node_def); + } + } + initializations.add(node.name.name, node); + return true; // don't go in nested scopes + } + if (node instanceof AST_Definitions && scope === self) { + node.definitions.forEach(function(def){ + if (!drop_vars) { + var node_def = def.name.definition(); + if (!(node_def.id in in_use_ids)) { + in_use_ids[node_def.id] = true; + in_use.push(node_def); + } + } + if (def.value) { + initializations.add(def.name.name, def.value); + if (def.value.has_side_effects(compressor)) { + def.value.walk(tw); + } + } + }); + return true; + } + if (assign_as_unused + && node instanceof AST_Assign + && node.operator == "=" + && node.left instanceof AST_SymbolRef + && scope === self) { + node.right.walk(tw); + return true; + } + if (node instanceof AST_SymbolRef) { + var node_def = node.definition(); + if (!(node_def.id in in_use_ids)) { + in_use_ids[node_def.id] = true; + in_use.push(node_def); + } + return true; + } + if (node instanceof AST_Scope) { + var save_scope = scope; + scope = node; + descend(); + scope = save_scope; + return true; + } + } + }); + self.walk(tw); + // pass 2: for every used symbol we need to walk its + // initialization code to figure out if it uses other + // symbols (that may not be in_use). + for (var i = 0; i < in_use.length; ++i) { + in_use[i].orig.forEach(function(decl){ + // undeclared globals will be instanceof AST_SymbolRef + var init = initializations.get(decl.name); + if (init) init.forEach(function(init){ + var tw = new TreeWalker(function(node){ + if (node instanceof AST_SymbolRef) { + var node_def = node.definition(); + if (!(node_def.id in in_use_ids)) { + in_use_ids[node_def.id] = true; + in_use.push(node_def); + } + } + }); + init.walk(tw); + }); + }); + } + // pass 3: we should drop declarations not in_use + var tt = new TreeTransformer( + function before(node, descend, in_list) { + if (node instanceof AST_Function + && node.name + && !compressor.option("keep_fnames")) { + var def = node.name.definition(); + // any declarations with same name will overshadow + // name of this anonymous function and can therefore + // never be used anywhere + if (!(def.id in in_use_ids) || def.orig.length > 1) + node.name = null; + } + if (node instanceof AST_Lambda && !(node instanceof AST_Accessor)) { + var trim = !compressor.option("keep_fargs"); + for (var a = node.argnames, i = a.length; --i >= 0;) { + var sym = a[i]; + if (!(sym.definition().id in in_use_ids)) { + sym.__unused = true; + if (trim) { + a.pop(); + compressor[sym.unreferenced() ? "warn" : "info"]("Dropping unused function argument {name} [{file}:{line},{col}]", { + name : sym.name, + file : sym.start.file, + line : sym.start.line, + col : sym.start.col + }); + } + } + else { + trim = false; + } + } + } + if (drop_funcs && node instanceof AST_Defun && node !== self) { + if (!(node.name.definition().id in in_use_ids)) { + compressor[node.name.unreferenced() ? "warn" : "info"]("Dropping unused function {name} [{file}:{line},{col}]", { + name : node.name.name, + file : node.name.start.file, + line : node.name.start.line, + col : node.name.start.col + }); + return make_node(AST_EmptyStatement, node); + } + return node; + } + if (drop_vars && node instanceof AST_Definitions && !(tt.parent() instanceof AST_ForIn)) { + var def = node.definitions.filter(function(def){ + if (def.value) def.value = def.value.transform(tt); + var sym = def.name.definition(); + if (sym.id in in_use_ids) return true; + if (sym.orig[0] instanceof AST_SymbolCatch) { + def.value = def.value && def.value.drop_side_effect_free(compressor); + return true; + } + var w = { + name : def.name.name, + file : def.name.start.file, + line : def.name.start.line, + col : def.name.start.col + }; + if (def.value && (def._unused_side_effects = def.value.drop_side_effect_free(compressor))) { + compressor.warn("Side effects in initialization of unused variable {name} [{file}:{line},{col}]", w); + return true; + } + compressor[def.name.unreferenced() ? "warn" : "info"]("Dropping unused variable {name} [{file}:{line},{col}]", w); + return false; + }); + // place uninitialized names at the start + def = mergeSort(def, function(a, b){ + if (!a.value && b.value) return -1; + if (!b.value && a.value) return 1; + return 0; + }); + // for unused names whose initialization has + // side effects, we can cascade the init. code + // into the next one, or next statement. + var side_effects = []; + for (var i = 0; i < def.length;) { + var x = def[i]; + if (x._unused_side_effects) { + side_effects.push(x._unused_side_effects); + def.splice(i, 1); + } else { + if (side_effects.length > 0) { + side_effects.push(x.value); + x.value = AST_Seq.from_array(side_effects); + side_effects = []; + } + ++i; + } + } + if (side_effects.length > 0) { + side_effects = make_node(AST_BlockStatement, node, { + body: [ make_node(AST_SimpleStatement, node, { + body: AST_Seq.from_array(side_effects) + }) ] + }); + } else { + side_effects = null; + } + if (def.length == 0 && !side_effects) { + return make_node(AST_EmptyStatement, node); + } + if (def.length == 0) { + return in_list ? MAP.splice(side_effects.body) : side_effects; + } + node.definitions = def; + if (side_effects) { + side_effects.body.unshift(node); + return in_list ? MAP.splice(side_effects.body) : side_effects; + } + return node; + } + if (drop_vars && assign_as_unused + && node instanceof AST_Assign + && node.operator == "=" + && node.left instanceof AST_SymbolRef) { + var def = node.left.definition(); + if (!(def.id in in_use_ids) + && self.variables.get(def.name) === def) { + return maintain_this_binding(tt.parent(), node, node.right.transform(tt)); + } + } + if (node instanceof AST_For) { + descend(node, this); + + if (node.init instanceof AST_BlockStatement) { + // certain combination of unused name + side effect leads to: + // https://github.com/mishoo/UglifyJS2/issues/44 + // that's an invalid AST. + // We fix it at this stage by moving the `var` outside the `for`. + + var body = node.init.body.slice(0, -1); + node.init = node.init.body.slice(-1)[0].body; + body.push(node); + + return in_list ? MAP.splice(body) : make_node(AST_BlockStatement, node, { + body: body + }); + } else if (is_empty(node.init)) { + node.init = null; + return node; + } + } + if (node instanceof AST_Scope && node !== self) + return node; + } + ); + self.transform(tt); + } + }); + + AST_Scope.DEFMETHOD("hoist_declarations", function(compressor){ + var self = this; + if (compressor.has_directive("use asm")) return self; + var hoist_funs = compressor.option("hoist_funs"); + var hoist_vars = compressor.option("hoist_vars"); + if (hoist_funs || hoist_vars) { + var dirs = []; + var hoisted = []; + var vars = new Dictionary(), vars_found = 0, var_decl = 0; + // let's count var_decl first, we seem to waste a lot of + // space if we hoist `var` when there's only one. + self.walk(new TreeWalker(function(node){ + if (node instanceof AST_Scope && node !== self) + return true; + if (node instanceof AST_Var) { + ++var_decl; + return true; + } + })); + hoist_vars = hoist_vars && var_decl > 1; + var tt = new TreeTransformer( + function before(node) { + if (node !== self) { + if (node instanceof AST_Directive) { + dirs.push(node); + return make_node(AST_EmptyStatement, node); + } + if (node instanceof AST_Defun && hoist_funs) { + hoisted.push(node); + return make_node(AST_EmptyStatement, node); + } + if (node instanceof AST_Var && hoist_vars) { + node.definitions.forEach(function(def){ + vars.set(def.name.name, def); + ++vars_found; + }); + var seq = node.to_assignments(compressor); + var p = tt.parent(); + if (p instanceof AST_ForIn && p.init === node) { + if (seq == null) { + var def = node.definitions[0].name; + return make_node(AST_SymbolRef, def, def); + } + return seq; + } + if (p instanceof AST_For && p.init === node) { + return seq; + } + if (!seq) return make_node(AST_EmptyStatement, node); + return make_node(AST_SimpleStatement, node, { + body: seq + }); + } + if (node instanceof AST_Scope) + return node; // to avoid descending in nested scopes + } + } + ); + self = self.transform(tt); + if (vars_found > 0) { + // collect only vars which don't show up in self's arguments list + var defs = []; + vars.each(function(def, name){ + if (self instanceof AST_Lambda + && find_if(function(x){ return x.name == def.name.name }, + self.argnames)) { + vars.del(name); + } else { + def = def.clone(); + def.value = null; + defs.push(def); + vars.set(name, def); + } + }); + if (defs.length > 0) { + // try to merge in assignments + for (var i = 0; i < self.body.length;) { + if (self.body[i] instanceof AST_SimpleStatement) { + var expr = self.body[i].body, sym, assign; + if (expr instanceof AST_Assign + && expr.operator == "=" + && (sym = expr.left) instanceof AST_Symbol + && vars.has(sym.name)) + { + var def = vars.get(sym.name); + if (def.value) break; + def.value = expr.right; + remove(defs, def); + defs.push(def); + self.body.splice(i, 1); + continue; + } + if (expr instanceof AST_Seq + && (assign = expr.car) instanceof AST_Assign + && assign.operator == "=" + && (sym = assign.left) instanceof AST_Symbol + && vars.has(sym.name)) + { + var def = vars.get(sym.name); + if (def.value) break; + def.value = assign.right; + remove(defs, def); + defs.push(def); + self.body[i].body = expr.cdr; + continue; + } + } + if (self.body[i] instanceof AST_EmptyStatement) { + self.body.splice(i, 1); + continue; + } + if (self.body[i] instanceof AST_BlockStatement) { + var tmp = [ i, 1 ].concat(self.body[i].body); + self.body.splice.apply(self.body, tmp); + continue; + } + break; + } + defs = make_node(AST_Var, self, { + definitions: defs + }); + hoisted.push(defs); + }; + } + self.body = dirs.concat(hoisted, self.body); + } + return self; + }); + + // drop_side_effect_free() + // remove side-effect-free parts which only affects return value + (function(def){ + // Drop side-effect-free elements from an array of expressions. + // Returns an array of expressions with side-effects or null + // if all elements were dropped. Note: original array may be + // returned if nothing changed. + function trim(nodes, compressor, first_in_statement) { + var ret = [], changed = false; + for (var i = 0, len = nodes.length; i < len; i++) { + var node = nodes[i].drop_side_effect_free(compressor, first_in_statement); + changed |= node !== nodes[i]; + if (node) { + ret.push(node); + first_in_statement = false; + } + } + return changed ? ret.length ? ret : null : nodes; + } + + def(AST_Node, return_this); + def(AST_Constant, return_null); + def(AST_This, return_null); + def(AST_Call, function(compressor, first_in_statement){ + if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) { + if (this.expression instanceof AST_Function + && (!this.expression.name || !this.expression.name.definition().references.length)) { + var node = this.clone(); + node.expression = node.expression.process_expression(false, compressor); + return node; + } + return this; + } + if (this.pure) { + compressor.warn("Dropping __PURE__ call [{file}:{line},{col}]", this.start); + this.pure.value = this.pure.value.replace(/[@#]__PURE__/g, ' '); + } + var args = trim(this.args, compressor, first_in_statement); + return args && AST_Seq.from_array(args); + }); + def(AST_Function, return_null); + def(AST_Binary, function(compressor, first_in_statement){ + var right = this.right.drop_side_effect_free(compressor); + if (!right) return this.left.drop_side_effect_free(compressor, first_in_statement); + switch (this.operator) { + case "&&": + case "||": + if (right === this.right) return this; + var node = this.clone(); + node.right = right; + return node; + default: + var left = this.left.drop_side_effect_free(compressor, first_in_statement); + if (!left) return this.right.drop_side_effect_free(compressor, first_in_statement); + return make_node(AST_Seq, this, { + car: left, + cdr: right + }); + } + }); + def(AST_Assign, return_this); + def(AST_Conditional, function(compressor){ + var consequent = this.consequent.drop_side_effect_free(compressor); + var alternative = this.alternative.drop_side_effect_free(compressor); + if (consequent === this.consequent && alternative === this.alternative) return this; + if (!consequent) return alternative ? make_node(AST_Binary, this, { + operator: "||", + left: this.condition, + right: alternative + }) : this.condition.drop_side_effect_free(compressor); + if (!alternative) return make_node(AST_Binary, this, { + operator: "&&", + left: this.condition, + right: consequent + }); + var node = this.clone(); + node.consequent = consequent; + node.alternative = alternative; + return node; + }); + def(AST_Unary, function(compressor, first_in_statement){ + if (unary_side_effects(this.operator)) return this; + if (this.operator == "typeof" && this.expression instanceof AST_SymbolRef) return null; + var expression = this.expression.drop_side_effect_free(compressor, first_in_statement); + if (first_in_statement + && this instanceof AST_UnaryPrefix + && is_iife_call(expression)) { + if (expression === this.expression && this.operator.length === 1) return this; + return make_node(AST_UnaryPrefix, this, { + operator: this.operator.length === 1 ? this.operator : "!", + expression: expression + }); + } + return expression; + }); + def(AST_SymbolRef, function() { + return this.undeclared() ? this : null; + }); + def(AST_Object, function(compressor, first_in_statement){ + var values = trim(this.properties, compressor, first_in_statement); + return values && AST_Seq.from_array(values); + }); + def(AST_ObjectProperty, function(compressor, first_in_statement){ + return this.value.drop_side_effect_free(compressor, first_in_statement); + }); + def(AST_Array, function(compressor, first_in_statement){ + var values = trim(this.elements, compressor, first_in_statement); + return values && AST_Seq.from_array(values); + }); + def(AST_Dot, function(compressor, first_in_statement){ + if (this.expression.may_eq_null(compressor)) return this; + return this.expression.drop_side_effect_free(compressor, first_in_statement); + }); + def(AST_Sub, function(compressor, first_in_statement){ + if (this.expression.may_eq_null(compressor)) return this; + var expression = this.expression.drop_side_effect_free(compressor, first_in_statement); + if (!expression) return this.property.drop_side_effect_free(compressor, first_in_statement); + var property = this.property.drop_side_effect_free(compressor); + if (!property) return expression; + return make_node(AST_Seq, this, { + car: expression, + cdr: property + }); + }); + def(AST_Seq, function(compressor){ + var cdr = this.cdr.drop_side_effect_free(compressor); + if (cdr === this.cdr) return this; + if (!cdr) return this.car; + return make_node(AST_Seq, this, { + car: this.car, + cdr: cdr + }); + }); + })(function(node, func){ + node.DEFMETHOD("drop_side_effect_free", func); + }); + + OPT(AST_SimpleStatement, function(self, compressor){ + if (compressor.option("side_effects")) { + var body = self.body; + var node = body.drop_side_effect_free(compressor, true); + if (!node) { + compressor.warn("Dropping side-effect-free statement [{file}:{line},{col}]", self.start); + return make_node(AST_EmptyStatement, self); + } + if (node !== body) { + return make_node(AST_SimpleStatement, self, { body: node }); + } + } + return self; + }); + + OPT(AST_DWLoop, function(self, compressor){ + if (!compressor.option("loops")) return self; + var cond = self.condition.evaluate(compressor); + if (cond !== self.condition) { + if (cond) { + return make_node(AST_For, self, { + body: self.body + }); + } + if (compressor.option("dead_code") && self instanceof AST_While) { + var a = []; + extract_declarations_from_unreachable_code(compressor, self.body, a); + return make_node(AST_BlockStatement, self, { body: a }); + } + if (self instanceof AST_Do) { + var has_loop_control = false; + var tw = new TreeWalker(function(node) { + if (node instanceof AST_Scope || has_loop_control) return true; + if (node instanceof AST_LoopControl && tw.loopcontrol_target(node) === self) + return has_loop_control = true; + }); + self.walk(tw); + if (!has_loop_control) return self.body; + } + } + if (self instanceof AST_While) { + return make_node(AST_For, self, self).optimize(compressor); + } + return self; + }); + + function if_break_in_loop(self, compressor) { + function drop_it(rest) { + rest = as_statement_array(rest); + if (self.body instanceof AST_BlockStatement) { + self.body = self.body.clone(); + self.body.body = rest.concat(self.body.body.slice(1)); + self.body = self.body.transform(compressor); + } else { + self.body = make_node(AST_BlockStatement, self.body, { + body: rest + }).transform(compressor); + } + if_break_in_loop(self, compressor); + } + var first = self.body instanceof AST_BlockStatement ? self.body.body[0] : self.body; + if (first instanceof AST_If) { + if (first.body instanceof AST_Break + && compressor.loopcontrol_target(first.body) === compressor.self()) { + if (self.condition) { + self.condition = make_node(AST_Binary, self.condition, { + left: self.condition, + operator: "&&", + right: first.condition.negate(compressor), + }); + } else { + self.condition = first.condition.negate(compressor); + } + drop_it(first.alternative); + } + else if (first.alternative instanceof AST_Break + && compressor.loopcontrol_target(first.alternative) === compressor.self()) { + if (self.condition) { + self.condition = make_node(AST_Binary, self.condition, { + left: self.condition, + operator: "&&", + right: first.condition, + }); + } else { + self.condition = first.condition; + } + drop_it(first.body); + } + } + }; + + OPT(AST_For, function(self, compressor){ + if (!compressor.option("loops")) return self; + if (self.condition) { + var cond = self.condition.evaluate(compressor); + if (compressor.option("dead_code") && !cond) { + var a = []; + if (self.init instanceof AST_Statement) { + a.push(self.init); + } + else if (self.init) { + a.push(make_node(AST_SimpleStatement, self.init, { + body: self.init + })); + } + extract_declarations_from_unreachable_code(compressor, self.body, a); + return make_node(AST_BlockStatement, self, { body: a }); + } + if (cond !== self.condition) { + cond = make_node_from_constant(cond, self.condition).transform(compressor); + self.condition = best_of_expression(cond, self.condition); + } + } + if_break_in_loop(self, compressor); + return self; + }); + + OPT(AST_If, function(self, compressor){ + if (is_empty(self.alternative)) self.alternative = null; + + if (!compressor.option("conditionals")) return self; + // if condition can be statically determined, warn and drop + // one of the blocks. note, statically determined implies + // “has no side effects”; also it doesn't work for cases like + // `x && true`, though it probably should. + var cond = self.condition.evaluate(compressor); + if (cond !== self.condition) { + if (cond) { + compressor.warn("Condition always true [{file}:{line},{col}]", self.condition.start); + if (compressor.option("dead_code")) { + var a = []; + if (self.alternative) { + extract_declarations_from_unreachable_code(compressor, self.alternative, a); + } + a.push(self.body); + return make_node(AST_BlockStatement, self, { body: a }).optimize(compressor); + } + } else { + compressor.warn("Condition always false [{file}:{line},{col}]", self.condition.start); + if (compressor.option("dead_code")) { + var a = []; + extract_declarations_from_unreachable_code(compressor, self.body, a); + if (self.alternative) a.push(self.alternative); + return make_node(AST_BlockStatement, self, { body: a }).optimize(compressor); + } + } + cond = make_node_from_constant(cond, self.condition).transform(compressor); + self.condition = best_of_expression(cond, self.condition); + } + var negated = self.condition.negate(compressor); + var self_condition_length = self.condition.print_to_string().length; + var negated_length = negated.print_to_string().length; + var negated_is_best = negated_length < self_condition_length; + if (self.alternative && negated_is_best) { + negated_is_best = false; // because we already do the switch here. + // no need to swap values of self_condition_length and negated_length + // here because they are only used in an equality comparison later on. + self.condition = negated; + var tmp = self.body; + self.body = self.alternative || make_node(AST_EmptyStatement, self); + self.alternative = tmp; + } + if (is_empty(self.body) && is_empty(self.alternative)) { + return make_node(AST_SimpleStatement, self.condition, { + body: self.condition.clone() + }).optimize(compressor); + } + if (self.body instanceof AST_SimpleStatement + && self.alternative instanceof AST_SimpleStatement) { + return make_node(AST_SimpleStatement, self, { + body: make_node(AST_Conditional, self, { + condition : self.condition, + consequent : self.body.body, + alternative : self.alternative.body + }) + }).optimize(compressor); + } + if (is_empty(self.alternative) && self.body instanceof AST_SimpleStatement) { + if (self_condition_length === negated_length && !negated_is_best + && self.condition instanceof AST_Binary && self.condition.operator == "||") { + // although the code length of self.condition and negated are the same, + // negated does not require additional surrounding parentheses. + // see https://github.com/mishoo/UglifyJS2/issues/979 + negated_is_best = true; + } + if (negated_is_best) return make_node(AST_SimpleStatement, self, { + body: make_node(AST_Binary, self, { + operator : "||", + left : negated, + right : self.body.body + }) + }).optimize(compressor); + return make_node(AST_SimpleStatement, self, { + body: make_node(AST_Binary, self, { + operator : "&&", + left : self.condition, + right : self.body.body + }) + }).optimize(compressor); + } + if (self.body instanceof AST_EmptyStatement + && self.alternative instanceof AST_SimpleStatement) { + return make_node(AST_SimpleStatement, self, { + body: make_node(AST_Binary, self, { + operator : "||", + left : self.condition, + right : self.alternative.body + }) + }).optimize(compressor); + } + if (self.body instanceof AST_Exit + && self.alternative instanceof AST_Exit + && self.body.TYPE == self.alternative.TYPE) { + return make_node(self.body.CTOR, self, { + value: make_node(AST_Conditional, self, { + condition : self.condition, + consequent : self.body.value || make_node(AST_Undefined, self.body), + alternative : self.alternative.value || make_node(AST_Undefined, self.alternative) + }).transform(compressor) + }).optimize(compressor); + } + if (self.body instanceof AST_If + && !self.body.alternative + && !self.alternative) { + self = make_node(AST_If, self, { + condition: make_node(AST_Binary, self.condition, { + operator: "&&", + left: self.condition, + right: self.body.condition + }), + body: self.body.body, + alternative: null + }); + } + if (aborts(self.body)) { + if (self.alternative) { + var alt = self.alternative; + self.alternative = null; + return make_node(AST_BlockStatement, self, { + body: [ self, alt ] + }).optimize(compressor); + } + } + if (aborts(self.alternative)) { + var body = self.body; + self.body = self.alternative; + self.condition = negated_is_best ? negated : self.condition.negate(compressor); + self.alternative = null; + return make_node(AST_BlockStatement, self, { + body: [ self, body ] + }).optimize(compressor); + } + return self; + }); + + OPT(AST_Switch, function(self, compressor){ + if (!compressor.option("switches")) return self; + var branch; + var value = self.expression.evaluate(compressor); + if (value !== self.expression) { + var expression = make_node_from_constant(value, self.expression).transform(compressor); + self.expression = best_of_expression(expression, self.expression); + } + if (!compressor.option("dead_code")) return self; + var decl = []; + var body = []; + var default_branch; + var exact_match; + for (var i = 0, len = self.body.length; i < len && !exact_match; i++) { + branch = self.body[i]; + if (branch instanceof AST_Default) { + if (!default_branch) { + default_branch = branch; + } else { + eliminate_branch(branch, body[body.length - 1]); + } + } else if (value !== self.expression) { + var exp = branch.expression.evaluate(compressor); + if (exp === value) { + exact_match = branch; + if (default_branch) { + var default_index = body.indexOf(default_branch); + body.splice(default_index, 1); + eliminate_branch(default_branch, body[default_index - 1]); + default_branch = null; + } + } else if (exp !== branch.expression) { + eliminate_branch(branch, body[body.length - 1]); + continue; + } + } + if (aborts(branch)) { + var prev = body[body.length - 1]; + if (aborts(prev) && prev.body.length == branch.body.length + && make_node(AST_BlockStatement, prev, prev).equivalent_to(make_node(AST_BlockStatement, branch, branch))) { + prev.body = []; + } + } + body.push(branch); + } + while (i < len) eliminate_branch(self.body[i++], body[body.length - 1]); + if (body.length > 0) { + body[0].body = decl.concat(body[0].body); + } + self.body = body; + while (branch = body[body.length - 1]) { + var stat = branch.body[branch.body.length - 1]; + if (stat instanceof AST_Break && compressor.loopcontrol_target(stat) === self) + branch.body.pop(); + if (branch.body.length || branch instanceof AST_Case + && (default_branch || branch.expression.has_side_effects(compressor))) break; + if (body.pop() === default_branch) default_branch = null; + } + if (body.length == 0) { + return make_node(AST_BlockStatement, self, { + body: decl.concat(make_node(AST_SimpleStatement, self.expression, { + body: self.expression + })) + }).optimize(compressor); + } + if (body.length == 1 && (body[0] === exact_match || body[0] === default_branch)) { + var has_break = false; + var tw = new TreeWalker(function(node) { + if (has_break + || node instanceof AST_Lambda + || node instanceof AST_SimpleStatement) return true; + if (node instanceof AST_Break && tw.loopcontrol_target(node) === self) + has_break = true; + }); + self.walk(tw); + if (!has_break) { + body = body[0].body.slice(); + body.unshift(make_node(AST_SimpleStatement, self.expression, { + body: self.expression + })); + return make_node(AST_BlockStatement, self, { + body: body + }).optimize(compressor); + } + } + return self; + + function eliminate_branch(branch, prev) { + if (prev && !aborts(prev)) { + prev.body = prev.body.concat(branch.body); + } else { + extract_declarations_from_unreachable_code(compressor, branch, decl); + } + } + }); + + OPT(AST_Try, function(self, compressor){ + self.body = tighten_body(self.body, compressor); + if (self.bcatch && self.bfinally && all(self.bfinally.body, is_empty)) self.bfinally = null; + if (all(self.body, is_empty)) { + var body = []; + if (self.bcatch) extract_declarations_from_unreachable_code(compressor, self.bcatch, body); + if (self.bfinally) body = body.concat(self.bfinally.body); + return body.length > 0 ? make_node(AST_BlockStatement, self, { + body: body + }).optimize(compressor) : make_node(AST_EmptyStatement, self); + } + return self; + }); + + AST_Definitions.DEFMETHOD("remove_initializers", function(){ + this.definitions.forEach(function(def){ def.value = null }); + }); + + AST_Definitions.DEFMETHOD("to_assignments", function(compressor){ + var reduce_vars = compressor.option("reduce_vars"); + var assignments = this.definitions.reduce(function(a, def){ + if (def.value) { + var name = make_node(AST_SymbolRef, def.name, def.name); + a.push(make_node(AST_Assign, def, { + operator : "=", + left : name, + right : def.value + })); + if (reduce_vars) name.definition().fixed = false; + } + return a; + }, []); + if (assignments.length == 0) return null; + return AST_Seq.from_array(assignments); + }); + + OPT(AST_Definitions, function(self, compressor){ + if (self.definitions.length == 0) + return make_node(AST_EmptyStatement, self); + return self; + }); + + OPT(AST_Call, function(self, compressor){ + var exp = self.expression; + if (compressor.option("reduce_vars") + && exp instanceof AST_SymbolRef) { + var def = exp.definition(); + var fixed = exp.fixed_value(); + if (fixed instanceof AST_Defun) { + def.fixed = fixed = make_node(AST_Function, fixed, fixed).clone(true); + } + if (fixed instanceof AST_Function) { + exp = fixed; + if (compressor.option("unused") + && def.references.length == 1 + && !(def.scope.uses_arguments + && def.orig[0] instanceof AST_SymbolFunarg) + && !def.scope.uses_eval + && compressor.find_parent(AST_Scope) === def.scope) { + self.expression = exp; + } + } + } + if (compressor.option("unused") + && exp instanceof AST_Function + && !exp.uses_arguments + && !exp.uses_eval) { + var pos = 0, last = 0; + for (var i = 0, len = self.args.length; i < len; i++) { + var trim = i >= exp.argnames.length; + if (trim || exp.argnames[i].__unused) { + var node = self.args[i].drop_side_effect_free(compressor); + if (node) { + self.args[pos++] = node; + } else if (!trim) { + self.args[pos++] = make_node(AST_Number, self.args[i], { + value: 0 + }); + continue; + } + } else { + self.args[pos++] = self.args[i]; + } + last = pos; + } + self.args.length = last; + } + if (compressor.option("unsafe")) { + if (exp instanceof AST_SymbolRef && exp.undeclared()) { + switch (exp.name) { + case "Array": + if (self.args.length != 1) { + return make_node(AST_Array, self, { + elements: self.args + }).optimize(compressor); + } + break; + case "Object": + if (self.args.length == 0) { + return make_node(AST_Object, self, { + properties: [] + }); + } + break; + case "String": + if (self.args.length == 0) return make_node(AST_String, self, { + value: "" + }); + if (self.args.length <= 1) return make_node(AST_Binary, self, { + left: self.args[0], + operator: "+", + right: make_node(AST_String, self, { value: "" }) + }).optimize(compressor); + break; + case "Number": + if (self.args.length == 0) return make_node(AST_Number, self, { + value: 0 + }); + if (self.args.length == 1) return make_node(AST_UnaryPrefix, self, { + expression: self.args[0], + operator: "+" + }).optimize(compressor); + case "Boolean": + if (self.args.length == 0) return make_node(AST_False, self); + if (self.args.length == 1) return make_node(AST_UnaryPrefix, self, { + expression: make_node(AST_UnaryPrefix, self, { + expression: self.args[0], + operator: "!" + }), + operator: "!" + }).optimize(compressor); + break; + case "Function": + // new Function() => function(){} + if (self.args.length == 0) return make_node(AST_Function, self, { + argnames: [], + body: [] + }); + if (all(self.args, function(x){ return x instanceof AST_String })) { + // quite a corner-case, but we can handle it: + // https://github.com/mishoo/UglifyJS2/issues/203 + // if the code argument is a constant, then we can minify it. + try { + var code = "(function(" + self.args.slice(0, -1).map(function(arg){ + return arg.value; + }).join(",") + "){" + self.args[self.args.length - 1].value + "})()"; + var ast = parse(code); + ast.figure_out_scope({ screw_ie8: compressor.option("screw_ie8") }); + var comp = new Compressor(compressor.options); + ast = ast.transform(comp); + ast.figure_out_scope({ screw_ie8: compressor.option("screw_ie8") }); + ast.mangle_names(); + var fun; + try { + ast.walk(new TreeWalker(function(node){ + if (node instanceof AST_Lambda) { + fun = node; + throw ast; + } + })); + } catch(ex) { + if (ex !== ast) throw ex; + }; + if (!fun) return self; + var args = fun.argnames.map(function(arg, i){ + return make_node(AST_String, self.args[i], { + value: arg.print_to_string() + }); + }); + var code = OutputStream(); + AST_BlockStatement.prototype._codegen.call(fun, fun, code); + code = code.toString().replace(/^\{|\}$/g, ""); + args.push(make_node(AST_String, self.args[self.args.length - 1], { + value: code + })); + self.args = args; + return self; + } catch(ex) { + if (ex instanceof JS_Parse_Error) { + compressor.warn("Error parsing code passed to new Function [{file}:{line},{col}]", self.args[self.args.length - 1].start); + compressor.warn(ex.toString()); + } else { + console.log(ex); + throw ex; + } + } + } + break; + } + } + else if (exp instanceof AST_Dot && exp.property == "toString" && self.args.length == 0) { + return make_node(AST_Binary, self, { + left: make_node(AST_String, self, { value: "" }), + operator: "+", + right: exp.expression + }).optimize(compressor); + } + else if (exp instanceof AST_Dot && exp.expression instanceof AST_Array && exp.property == "join") EXIT: { + var separator; + if (self.args.length > 0) { + separator = self.args[0].evaluate(compressor); + if (separator === self.args[0]) break EXIT; // not a constant + } + var elements = []; + var consts = []; + exp.expression.elements.forEach(function(el) { + var value = el.evaluate(compressor); + if (value !== el) { + consts.push(value); + } else { + if (consts.length > 0) { + elements.push(make_node(AST_String, self, { + value: consts.join(separator) + })); + consts.length = 0; + } + elements.push(el); + } + }); + if (consts.length > 0) { + elements.push(make_node(AST_String, self, { + value: consts.join(separator) + })); + } + if (elements.length == 0) return make_node(AST_String, self, { value: "" }); + if (elements.length == 1) { + if (elements[0].is_string(compressor)) { + return elements[0]; + } + return make_node(AST_Binary, elements[0], { + operator : "+", + left : make_node(AST_String, self, { value: "" }), + right : elements[0] + }); + } + if (separator == "") { + var first; + if (elements[0].is_string(compressor) + || elements[1].is_string(compressor)) { + first = elements.shift(); + } else { + first = make_node(AST_String, self, { value: "" }); + } + return elements.reduce(function(prev, el){ + return make_node(AST_Binary, el, { + operator : "+", + left : prev, + right : el + }); + }, first).optimize(compressor); + } + // need this awkward cloning to not affect original element + // best_of will decide which one to get through. + var node = self.clone(); + node.expression = node.expression.clone(); + node.expression.expression = node.expression.expression.clone(); + node.expression.expression.elements = elements; + return best_of(compressor, self, node); + } + else if (exp instanceof AST_Dot && exp.expression.is_string(compressor) && exp.property == "charAt") { + var arg = self.args[0]; + var index = arg ? arg.evaluate(compressor) : 0; + if (index !== arg) { + return make_node(AST_Sub, exp, { + expression: exp.expression, + property: make_node_from_constant(index | 0, arg || exp) + }).optimize(compressor); + } + } + } + if (exp instanceof AST_Function) { + if (exp.body[0] instanceof AST_Return) { + var value = exp.body[0].value; + if (!value || value.is_constant()) { + var args = self.args.concat(value || make_node(AST_Undefined, self)); + return AST_Seq.from_array(args).transform(compressor); + } + } + if (compressor.option("side_effects") && all(exp.body, is_empty)) { + var args = self.args.concat(make_node(AST_Undefined, self)); + return AST_Seq.from_array(args).transform(compressor); + } + } + if (compressor.option("drop_console")) { + if (exp instanceof AST_PropAccess) { + var name = exp.expression; + while (name.expression) { + name = name.expression; + } + if (name instanceof AST_SymbolRef + && name.name == "console" + && name.undeclared()) { + return make_node(AST_Undefined, self).optimize(compressor); + } + } + } + if (compressor.option("negate_iife") + && compressor.parent() instanceof AST_SimpleStatement + && is_iife_call(self)) { + return self.negate(compressor, true); + } + return self; + }); + + OPT(AST_New, function(self, compressor){ + if (compressor.option("unsafe")) { + var exp = self.expression; + if (exp instanceof AST_SymbolRef && exp.undeclared()) { + switch (exp.name) { + case "Object": + case "RegExp": + case "Function": + case "Error": + case "Array": + return make_node(AST_Call, self, self).transform(compressor); + } + } + } + return self; + }); + + OPT(AST_Seq, function(self, compressor){ + if (!compressor.option("side_effects")) + return self; + self.car = self.car.drop_side_effect_free(compressor, first_in_statement(compressor)); + if (!self.car) return maintain_this_binding(compressor.parent(), self, self.cdr); + if (compressor.option("cascade")) { + var left; + if (self.car instanceof AST_Assign + && !self.car.left.has_side_effects(compressor)) { + left = self.car.left; + } else if (self.car instanceof AST_Unary + && (self.car.operator == "++" || self.car.operator == "--")) { + left = self.car.expression; + } + if (left + && !(left instanceof AST_SymbolRef + && left.definition().orig[0] instanceof AST_SymbolLambda)) { + var parent, field; + var cdr = self.cdr; + while (true) { + if (cdr.equivalent_to(left)) { + var car = self.car instanceof AST_UnaryPostfix ? make_node(AST_UnaryPrefix, self.car, { + operator: self.car.operator, + expression: left + }) : self.car; + if (parent) { + parent[field] = car; + return self.cdr; + } + return car; + } + if (cdr instanceof AST_Binary && !(cdr instanceof AST_Assign)) { + if (cdr.left.is_constant()) { + if (cdr.operator == "||" || cdr.operator == "&&") break; + field = "right"; + } else { + field = "left"; + } + } else if (cdr instanceof AST_Call + || cdr instanceof AST_Unary && !unary_side_effects(cdr.operator)) { + field = "expression"; + } else break; + parent = cdr; + cdr = cdr[field]; + } + } + } + if (is_undefined(self.cdr, compressor)) { + return make_node(AST_UnaryPrefix, self, { + operator : "void", + expression : self.car + }); + } + return self; + }); + + AST_Unary.DEFMETHOD("lift_sequences", function(compressor){ + if (compressor.option("sequences")) { + if (this.expression instanceof AST_Seq) { + var seq = this.expression; + var x = seq.to_array(); + var e = this.clone(); + e.expression = x.pop(); + x.push(e); + seq = AST_Seq.from_array(x).transform(compressor); + return seq; + } + } + return this; + }); + + OPT(AST_UnaryPostfix, function(self, compressor){ + return self.lift_sequences(compressor); + }); + + OPT(AST_UnaryPrefix, function(self, compressor){ + var e = self.expression; + if (self.operator == "delete" + && !(e instanceof AST_SymbolRef + || e instanceof AST_PropAccess + || e instanceof AST_NaN + || e instanceof AST_Infinity + || e instanceof AST_Undefined)) { + if (e instanceof AST_Seq) { + e = e.to_array(); + e.push(make_node(AST_True, self)); + return AST_Seq.from_array(e).optimize(compressor); + } + return make_node(AST_Seq, self, { + car: e, + cdr: make_node(AST_True, self) + }).optimize(compressor); + } + var seq = self.lift_sequences(compressor); + if (seq !== self) { + return seq; + } + if (compressor.option("side_effects") && self.operator == "void") { + e = e.drop_side_effect_free(compressor); + if (e) { + self.expression = e; + return self; + } else { + return make_node(AST_Undefined, self).optimize(compressor); + } + } + if (compressor.option("booleans") && compressor.in_boolean_context()) { + switch (self.operator) { + case "!": + if (e instanceof AST_UnaryPrefix && e.operator == "!") { + // !!foo ==> foo, if we're in boolean context + return e.expression; + } + if (e instanceof AST_Binary) { + self = best_of(compressor, self, e.negate(compressor, first_in_statement(compressor))); + } + break; + case "typeof": + // typeof always returns a non-empty string, thus it's + // always true in booleans + compressor.warn("Boolean expression always true [{file}:{line},{col}]", self.start); + return (e instanceof AST_SymbolRef ? make_node(AST_True, self) : make_node(AST_Seq, self, { + car: e, + cdr: make_node(AST_True, self) + })).optimize(compressor); + } + } + if (self.operator == "-" && e instanceof AST_Infinity) { + e = e.transform(compressor); + } + if (e instanceof AST_Binary + && (self.operator == "+" || self.operator == "-") + && (e.operator == "*" || e.operator == "/" || e.operator == "%")) { + return make_node(AST_Binary, self, { + operator: e.operator, + left: make_node(AST_UnaryPrefix, e.left, { + operator: self.operator, + expression: e.left + }), + right: e.right + }); + } + // avoids infinite recursion of numerals + if (self.operator != "-" + || !(e instanceof AST_Number || e instanceof AST_Infinity)) { + var ev = self.evaluate(compressor); + if (ev !== self) { + ev = make_node_from_constant(ev, self).optimize(compressor); + return best_of(compressor, ev, self); + } + } + return self; + }); + + AST_Binary.DEFMETHOD("lift_sequences", function(compressor){ + if (compressor.option("sequences")) { + if (this.left instanceof AST_Seq) { + var seq = this.left; + var x = seq.to_array(); + var e = this.clone(); + e.left = x.pop(); + x.push(e); + return AST_Seq.from_array(x).optimize(compressor); + } + if (this.right instanceof AST_Seq && !this.left.has_side_effects(compressor)) { + var assign = this.operator == "=" && this.left instanceof AST_SymbolRef; + var root = this.right.clone(); + var cursor, seq = root; + while (assign || !seq.car.has_side_effects(compressor)) { + cursor = seq; + if (seq.cdr instanceof AST_Seq) { + seq = seq.cdr = seq.cdr.clone(); + } else break; + } + if (cursor) { + var e = this.clone(); + e.right = cursor.cdr; + cursor.cdr = e; + return root.optimize(compressor); + } + } + } + return this; + }); + + var commutativeOperators = makePredicate("== === != !== * & | ^"); + + OPT(AST_Binary, function(self, compressor){ + function reversible() { + return self.left.is_constant() + || self.right.is_constant() + || !self.left.has_side_effects(compressor) + && !self.right.has_side_effects(compressor); + } + function reverse(op) { + if (reversible()) { + if (op) self.operator = op; + var tmp = self.left; + self.left = self.right; + self.right = tmp; + } + } + if (commutativeOperators(self.operator)) { + if (self.right.is_constant() + && !self.left.is_constant()) { + // if right is a constant, whatever side effects the + // left side might have could not influence the + // result. hence, force switch. + + if (!(self.left instanceof AST_Binary + && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) { + reverse(); + } + } + } + self = self.lift_sequences(compressor); + if (compressor.option("comparisons")) switch (self.operator) { + case "===": + case "!==": + if ((self.left.is_string(compressor) && self.right.is_string(compressor)) || + (self.left.is_number(compressor) && self.right.is_number(compressor)) || + (self.left.is_boolean() && self.right.is_boolean())) { + self.operator = self.operator.substr(0, 2); + } + // XXX: intentionally falling down to the next case + case "==": + case "!=": + // "undefined" == typeof x => undefined === x + if (self.left instanceof AST_String + && self.left.value == "undefined" + && self.right instanceof AST_UnaryPrefix + && self.right.operator == "typeof") { + var expr = self.right.expression; + if (expr instanceof AST_SymbolRef ? !expr.undeclared() + : !(expr instanceof AST_PropAccess) || compressor.option("screw_ie8")) { + self.right = expr; + self.left = make_node(AST_Undefined, self.left).optimize(compressor); + if (self.operator.length == 2) self.operator += "="; + } + } + break; + } + if (compressor.option("booleans") && self.operator == "+" && compressor.in_boolean_context()) { + var ll = self.left.evaluate(compressor); + var rr = self.right.evaluate(compressor); + if (ll && typeof ll == "string") { + compressor.warn("+ in boolean context always true [{file}:{line},{col}]", self.start); + return make_node(AST_Seq, self, { + car: self.right, + cdr: make_node(AST_True, self) + }).optimize(compressor); + } + if (rr && typeof rr == "string") { + compressor.warn("+ in boolean context always true [{file}:{line},{col}]", self.start); + return make_node(AST_Seq, self, { + car: self.left, + cdr: make_node(AST_True, self) + }).optimize(compressor); + } + } + if (compressor.option("comparisons") && self.is_boolean()) { + if (!(compressor.parent() instanceof AST_Binary) + || compressor.parent() instanceof AST_Assign) { + var negated = make_node(AST_UnaryPrefix, self, { + operator: "!", + expression: self.negate(compressor, first_in_statement(compressor)) + }); + self = best_of(compressor, self, negated); + } + if (compressor.option("unsafe_comps")) { + switch (self.operator) { + case "<": reverse(">"); break; + case "<=": reverse(">="); break; + } + } + } + if (self.operator == "+") { + if (self.right instanceof AST_String + && self.right.getValue() == "" + && self.left.is_string(compressor)) { + return self.left; + } + if (self.left instanceof AST_String + && self.left.getValue() == "" + && self.right.is_string(compressor)) { + return self.right; + } + if (self.left instanceof AST_Binary + && self.left.operator == "+" + && self.left.left instanceof AST_String + && self.left.left.getValue() == "" + && self.right.is_string(compressor)) { + self.left = self.left.right; + return self.transform(compressor); + } + } + if (compressor.option("evaluate")) { + switch (self.operator) { + case "&&": + var ll = self.left.evaluate(compressor); + if (!ll) { + compressor.warn("Condition left of && always false [{file}:{line},{col}]", self.start); + return maintain_this_binding(compressor.parent(), self, self.left).optimize(compressor); + } else if (ll !== self.left) { + compressor.warn("Condition left of && always true [{file}:{line},{col}]", self.start); + return maintain_this_binding(compressor.parent(), self, self.right).optimize(compressor); + } + if (compressor.option("booleans") && compressor.in_boolean_context()) { + var rr = self.right.evaluate(compressor); + if (!rr) { + compressor.warn("Boolean && always false [{file}:{line},{col}]", self.start); + return make_node(AST_Seq, self, { + car: self.left, + cdr: make_node(AST_False, self) + }).optimize(compressor); + } else if (rr !== self.right) { + compressor.warn("Dropping side-effect-free && in boolean context [{file}:{line},{col}]", self.start); + return self.left.optimize(compressor); + } + } + break; + case "||": + var ll = self.left.evaluate(compressor); + if (!ll) { + compressor.warn("Condition left of || always false [{file}:{line},{col}]", self.start); + return maintain_this_binding(compressor.parent(), self, self.right).optimize(compressor); + } else if (ll !== self.left) { + compressor.warn("Condition left of || always true [{file}:{line},{col}]", self.start); + return maintain_this_binding(compressor.parent(), self, self.left).optimize(compressor); + } + if (compressor.option("booleans") && compressor.in_boolean_context()) { + var rr = self.right.evaluate(compressor); + if (!rr) { + compressor.warn("Dropping side-effect-free || in boolean context [{file}:{line},{col}]", self.start); + return self.left.optimize(compressor); + } else if (rr !== self.right) { + compressor.warn("Boolean || always true [{file}:{line},{col}]", self.start); + return make_node(AST_Seq, self, { + car: self.left, + cdr: make_node(AST_True, self) + }).optimize(compressor); + } + } + break; + } + var associative = true; + switch (self.operator) { + case "+": + // "foo" + ("bar" + x) => "foobar" + x + if (self.left instanceof AST_Constant + && self.right instanceof AST_Binary + && self.right.operator == "+" + && self.right.left instanceof AST_Constant + && self.right.is_string(compressor)) { + self = make_node(AST_Binary, self, { + operator: "+", + left: make_node(AST_String, self.left, { + value: "" + self.left.getValue() + self.right.left.getValue(), + start: self.left.start, + end: self.right.left.end + }), + right: self.right.right + }); + } + // (x + "foo") + "bar" => x + "foobar" + if (self.right instanceof AST_Constant + && self.left instanceof AST_Binary + && self.left.operator == "+" + && self.left.right instanceof AST_Constant + && self.left.is_string(compressor)) { + self = make_node(AST_Binary, self, { + operator: "+", + left: self.left.left, + right: make_node(AST_String, self.right, { + value: "" + self.left.right.getValue() + self.right.getValue(), + start: self.left.right.start, + end: self.right.end + }) + }); + } + // (x + "foo") + ("bar" + y) => (x + "foobar") + y + if (self.left instanceof AST_Binary + && self.left.operator == "+" + && self.left.is_string(compressor) + && self.left.right instanceof AST_Constant + && self.right instanceof AST_Binary + && self.right.operator == "+" + && self.right.left instanceof AST_Constant + && self.right.is_string(compressor)) { + self = make_node(AST_Binary, self, { + operator: "+", + left: make_node(AST_Binary, self.left, { + operator: "+", + left: self.left.left, + right: make_node(AST_String, self.left.right, { + value: "" + self.left.right.getValue() + self.right.left.getValue(), + start: self.left.right.start, + end: self.right.left.end + }) + }), + right: self.right.right + }); + } + // a + -b => a - b + if (self.right instanceof AST_UnaryPrefix + && self.right.operator == "-" + && self.left.is_number(compressor)) { + self = make_node(AST_Binary, self, { + operator: "-", + left: self.left, + right: self.right.expression + }); + break; + } + // -a + b => b - a + if (self.left instanceof AST_UnaryPrefix + && self.left.operator == "-" + && reversible() + && self.right.is_number(compressor)) { + self = make_node(AST_Binary, self, { + operator: "-", + left: self.right, + right: self.left.expression + }); + break; + } + case "*": + associative = compressor.option("unsafe_math"); + case "&": + case "|": + case "^": + // a + +b => +b + a + if (self.left.is_number(compressor) + && self.right.is_number(compressor) + && reversible() + && !(self.left instanceof AST_Binary + && self.left.operator != self.operator + && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) { + var reversed = make_node(AST_Binary, self, { + operator: self.operator, + left: self.right, + right: self.left + }); + if (self.right instanceof AST_Constant + && !(self.left instanceof AST_Constant)) { + self = best_of(compressor, reversed, self); + } else { + self = best_of(compressor, self, reversed); + } + } + if (associative && self.is_number(compressor)) { + // a + (b + c) => (a + b) + c + if (self.right instanceof AST_Binary + && self.right.operator == self.operator) { + self = make_node(AST_Binary, self, { + operator: self.operator, + left: make_node(AST_Binary, self.left, { + operator: self.operator, + left: self.left, + right: self.right.left, + start: self.left.start, + end: self.right.left.end + }), + right: self.right.right + }); + } + // (n + 2) + 3 => 5 + n + // (2 * n) * 3 => 6 + n + if (self.right instanceof AST_Constant + && self.left instanceof AST_Binary + && self.left.operator == self.operator) { + if (self.left.left instanceof AST_Constant) { + self = make_node(AST_Binary, self, { + operator: self.operator, + left: make_node(AST_Binary, self.left, { + operator: self.operator, + left: self.left.left, + right: self.right, + start: self.left.left.start, + end: self.right.end + }), + right: self.left.right + }); + } else if (self.left.right instanceof AST_Constant) { + self = make_node(AST_Binary, self, { + operator: self.operator, + left: make_node(AST_Binary, self.left, { + operator: self.operator, + left: self.left.right, + right: self.right, + start: self.left.right.start, + end: self.right.end + }), + right: self.left.left + }); + } + } + // (a | 1) | (2 | d) => (3 | a) | b + if (self.left instanceof AST_Binary + && self.left.operator == self.operator + && self.left.right instanceof AST_Constant + && self.right instanceof AST_Binary + && self.right.operator == self.operator + && self.right.left instanceof AST_Constant) { + self = make_node(AST_Binary, self, { + operator: self.operator, + left: make_node(AST_Binary, self.left, { + operator: self.operator, + left: make_node(AST_Binary, self.left.left, { + operator: self.operator, + left: self.left.right, + right: self.right.left, + start: self.left.right.start, + end: self.right.left.end + }), + right: self.left.left + }), + right: self.right.right + }); + } + } + } + } + // x && (y && z) ==> x && y && z + // x || (y || z) ==> x || y || z + // x + ("y" + z) ==> x + "y" + z + // "x" + (y + "z")==> "x" + y + "z" + if (self.right instanceof AST_Binary + && self.right.operator == self.operator + && (self.operator == "&&" + || self.operator == "||" + || (self.operator == "+" + && (self.right.left.is_string(compressor) + || (self.left.is_string(compressor) + && self.right.right.is_string(compressor)))))) + { + self.left = make_node(AST_Binary, self.left, { + operator : self.operator, + left : self.left, + right : self.right.left + }); + self.right = self.right.right; + return self.transform(compressor); + } + var ev = self.evaluate(compressor); + if (ev !== self) { + ev = make_node_from_constant(ev, self).optimize(compressor); + return best_of(compressor, ev, self); + } + return self; + }); + + OPT(AST_SymbolRef, function(self, compressor){ + var def = self.resolve_defines(compressor); + if (def) { + return def.optimize(compressor); + } + // testing against !self.scope.uses_with first is an optimization + if (compressor.option("screw_ie8") + && self.undeclared() + && (!self.scope.uses_with || !compressor.find_parent(AST_With))) { + switch (self.name) { + case "undefined": + return make_node(AST_Undefined, self).optimize(compressor); + case "NaN": + return make_node(AST_NaN, self).optimize(compressor); + case "Infinity": + return make_node(AST_Infinity, self).optimize(compressor); + } + } + if (compressor.option("evaluate") && compressor.option("reduce_vars")) { + var d = self.definition(); + var fixed = self.fixed_value(); + if (fixed) { + if (d.should_replace === undefined) { + var init = fixed.evaluate(compressor); + if (init !== fixed) { + init = make_node_from_constant(init, fixed); + var value = best_of_expression(init.optimize(compressor), fixed).print_to_string().length; + var name = d.name.length; + var freq = d.references.length; + var overhead = d.global || !freq ? 0 : (name + 2 + value) / freq; + d.should_replace = value <= name + overhead ? init : false; + } else { + d.should_replace = false; + } + } + if (d.should_replace) { + return best_of_expression(d.should_replace.optimize(compressor), fixed).clone(true); + } + } + } + return self; + }); + + function is_atomic(lhs, self) { + return lhs instanceof AST_SymbolRef || lhs.TYPE === self.TYPE; + } + + OPT(AST_Undefined, function(self, compressor){ + if (compressor.option("unsafe")) { + var undef = find_variable(compressor, "undefined"); + if (undef) { + var ref = make_node(AST_SymbolRef, self, { + name : "undefined", + scope : undef.scope, + thedef : undef + }); + ref.is_undefined = true; + return ref; + } + } + var lhs = is_lhs(compressor.self(), compressor.parent()); + if (lhs && is_atomic(lhs, self)) return self; + return make_node(AST_UnaryPrefix, self, { + operator: "void", + expression: make_node(AST_Number, self, { + value: 0 + }) + }); + }); + + OPT(AST_Infinity, function(self, compressor){ + var lhs = is_lhs(compressor.self(), compressor.parent()); + if (lhs && is_atomic(lhs, self)) return self; + if (compressor.option("keep_infinity") + && !(lhs && !is_atomic(lhs, self)) + && !find_variable(compressor, "Infinity")) + return self; + return make_node(AST_Binary, self, { + operator: "/", + left: make_node(AST_Number, self, { + value: 1 + }), + right: make_node(AST_Number, self, { + value: 0 + }) + }); + }); + + OPT(AST_NaN, function(self, compressor){ + var lhs = is_lhs(compressor.self(), compressor.parent()); + if (lhs && !is_atomic(lhs, self) + || find_variable(compressor, "NaN")) { + return make_node(AST_Binary, self, { + operator: "/", + left: make_node(AST_Number, self, { + value: 0 + }), + right: make_node(AST_Number, self, { + value: 0 + }) + }); + } + return self; + }); + + var ASSIGN_OPS = [ '+', '-', '/', '*', '%', '>>', '<<', '>>>', '|', '^', '&' ]; + var ASSIGN_OPS_COMMUTATIVE = [ '*', '|', '^', '&' ]; + OPT(AST_Assign, function(self, compressor){ + self = self.lift_sequences(compressor); + if (self.operator == "=" && self.left instanceof AST_SymbolRef && self.right instanceof AST_Binary) { + // x = expr1 OP expr2 + if (self.right.left instanceof AST_SymbolRef + && self.right.left.name == self.left.name + && member(self.right.operator, ASSIGN_OPS)) { + // x = x - 2 ---> x -= 2 + self.operator = self.right.operator + "="; + self.right = self.right.right; + } + else if (self.right.right instanceof AST_SymbolRef + && self.right.right.name == self.left.name + && member(self.right.operator, ASSIGN_OPS_COMMUTATIVE) + && !self.right.left.has_side_effects(compressor)) { + // x = 2 & x ---> x &= 2 + self.operator = self.right.operator + "="; + self.right = self.right.left; + } + } + return self; + }); + + OPT(AST_Conditional, function(self, compressor){ + if (!compressor.option("conditionals")) return self; + if (self.condition instanceof AST_Seq) { + var car = self.condition.car; + self.condition = self.condition.cdr; + return AST_Seq.cons(car, self); + } + var cond = self.condition.evaluate(compressor); + if (cond !== self.condition) { + if (cond) { + compressor.warn("Condition always true [{file}:{line},{col}]", self.start); + return maintain_this_binding(compressor.parent(), self, self.consequent); + } else { + compressor.warn("Condition always false [{file}:{line},{col}]", self.start); + return maintain_this_binding(compressor.parent(), self, self.alternative); + } + } + var negated = cond.negate(compressor, first_in_statement(compressor)); + if (best_of(compressor, cond, negated) === negated) { + self = make_node(AST_Conditional, self, { + condition: negated, + consequent: self.alternative, + alternative: self.consequent + }); + } + var condition = self.condition; + var consequent = self.consequent; + var alternative = self.alternative; + // x?x:y --> x||y + if (condition instanceof AST_SymbolRef + && consequent instanceof AST_SymbolRef + && condition.definition() === consequent.definition()) { + return make_node(AST_Binary, self, { + operator: "||", + left: condition, + right: alternative + }); + } + // if (foo) exp = something; else exp = something_else; + // | + // v + // exp = foo ? something : something_else; + if (consequent instanceof AST_Assign + && alternative instanceof AST_Assign + && consequent.operator == alternative.operator + && consequent.left.equivalent_to(alternative.left) + && (!self.condition.has_side_effects(compressor) + || consequent.operator == "=" + && !consequent.left.has_side_effects(compressor))) { + return make_node(AST_Assign, self, { + operator: consequent.operator, + left: consequent.left, + right: make_node(AST_Conditional, self, { + condition: self.condition, + consequent: consequent.right, + alternative: alternative.right + }) + }); + } + // x ? y(a) : y(b) --> y(x ? a : b) + if (consequent instanceof AST_Call + && alternative.TYPE === consequent.TYPE + && consequent.args.length == 1 + && alternative.args.length == 1 + && consequent.expression.equivalent_to(alternative.expression) + && !consequent.expression.has_side_effects(compressor)) { + consequent.args[0] = make_node(AST_Conditional, self, { + condition: self.condition, + consequent: consequent.args[0], + alternative: alternative.args[0] + }); + return consequent; + } + // x?y?z:a:a --> x&&y?z:a + if (consequent instanceof AST_Conditional + && consequent.alternative.equivalent_to(alternative)) { + return make_node(AST_Conditional, self, { + condition: make_node(AST_Binary, self, { + left: self.condition, + operator: "&&", + right: consequent.condition + }), + consequent: consequent.consequent, + alternative: alternative + }); + } + // x ? y : y --> x, y + if (consequent.equivalent_to(alternative)) { + return make_node(AST_Seq, self, { + car: self.condition, + cdr: consequent + }).optimize(compressor); + } + + if (is_true(self.consequent)) { + if (is_false(self.alternative)) { + // c ? true : false ---> !!c + return booleanize(self.condition); + } + // c ? true : x ---> !!c || x + return make_node(AST_Binary, self, { + operator: "||", + left: booleanize(self.condition), + right: self.alternative + }); + } + if (is_false(self.consequent)) { + if (is_true(self.alternative)) { + // c ? false : true ---> !c + return booleanize(self.condition.negate(compressor)); + } + // c ? false : x ---> !c && x + return make_node(AST_Binary, self, { + operator: "&&", + left: booleanize(self.condition.negate(compressor)), + right: self.alternative + }); + } + if (is_true(self.alternative)) { + // c ? x : true ---> !c || x + return make_node(AST_Binary, self, { + operator: "||", + left: booleanize(self.condition.negate(compressor)), + right: self.consequent + }); + } + if (is_false(self.alternative)) { + // c ? x : false ---> !!c && x + return make_node(AST_Binary, self, { + operator: "&&", + left: booleanize(self.condition), + right: self.consequent + }); + } + + return self; + + function booleanize(node) { + if (node.is_boolean()) return node; + // !!expression + return make_node(AST_UnaryPrefix, node, { + operator: "!", + expression: node.negate(compressor) + }); + } + + // AST_True or !0 + function is_true(node) { + return node instanceof AST_True + || (node instanceof AST_UnaryPrefix + && node.operator == "!" + && node.expression instanceof AST_Constant + && !node.expression.value); + } + // AST_False or !1 + function is_false(node) { + return node instanceof AST_False + || (node instanceof AST_UnaryPrefix + && node.operator == "!" + && node.expression instanceof AST_Constant + && !!node.expression.value); + } + }); + + OPT(AST_Boolean, function(self, compressor){ + if (compressor.option("booleans")) { + var p = compressor.parent(); + if (p instanceof AST_Binary && (p.operator == "==" + || p.operator == "!=")) { + compressor.warn("Non-strict equality against boolean: {operator} {value} [{file}:{line},{col}]", { + operator : p.operator, + value : self.value, + file : p.start.file, + line : p.start.line, + col : p.start.col, + }); + return make_node(AST_Number, self, { + value: +self.value + }); + } + return make_node(AST_UnaryPrefix, self, { + operator: "!", + expression: make_node(AST_Number, self, { + value: 1 - self.value + }) + }); + } + return self; + }); + + OPT(AST_Sub, function(self, compressor){ + var prop = self.property; + if (prop instanceof AST_String && compressor.option("properties")) { + prop = prop.getValue(); + if (RESERVED_WORDS(prop) ? compressor.option("screw_ie8") : is_identifier_string(prop)) { + return make_node(AST_Dot, self, { + expression : self.expression, + property : prop + }).optimize(compressor); + } + var v = parseFloat(prop); + if (!isNaN(v) && v.toString() == prop) { + self.property = make_node(AST_Number, self.property, { + value: v + }); + } + } + var ev = self.evaluate(compressor); + if (ev !== self) { + ev = make_node_from_constant(ev, self).optimize(compressor); + return best_of(compressor, ev, self); + } + return self; + }); + + OPT(AST_Dot, function(self, compressor){ + var def = self.resolve_defines(compressor); + if (def) { + return def.optimize(compressor); + } + var prop = self.property; + if (RESERVED_WORDS(prop) && !compressor.option("screw_ie8")) { + return make_node(AST_Sub, self, { + expression : self.expression, + property : make_node(AST_String, self, { + value: prop + }) + }).optimize(compressor); + } + if (compressor.option("unsafe_proto") + && self.expression instanceof AST_Dot + && self.expression.property == "prototype") { + var exp = self.expression.expression; + if (exp instanceof AST_SymbolRef && exp.undeclared()) switch (exp.name) { + case "Array": + self.expression = make_node(AST_Array, self.expression, { + elements: [] + }); + break; + case "Object": + self.expression = make_node(AST_Object, self.expression, { + properties: [] + }); + break; + case "String": + self.expression = make_node(AST_String, self.expression, { + value: "" + }); + break; + } + } + var ev = self.evaluate(compressor); + if (ev !== self) { + ev = make_node_from_constant(ev, self).optimize(compressor); + return best_of(compressor, ev, self); + } + return self; + }); + + function literals_in_boolean_context(self, compressor) { + if (compressor.option("booleans") && compressor.in_boolean_context()) { + return best_of(compressor, self, make_node(AST_Seq, self, { + car: self, + cdr: make_node(AST_True, self) + }).optimize(compressor)); + } + return self; + }; + OPT(AST_Array, literals_in_boolean_context); + OPT(AST_Object, literals_in_boolean_context); + OPT(AST_RegExp, literals_in_boolean_context); + + OPT(AST_Return, function(self, compressor){ + if (self.value && is_undefined(self.value, compressor)) { + self.value = null; + } + return self; + }); + + OPT(AST_VarDef, function(self, compressor){ + var defines = compressor.option("global_defs"); + if (defines && HOP(defines, self.name.name)) { + compressor.warn('global_defs ' + self.name.name + ' redefined [{file}:{line},{col}]', self.start); + } + return self; + }); + +})(); |